Iam committed to building a united front against Donald Trump, and working with both Democratic and independent voters toward the best possible ticket and platform for the Democratic Party in November. But sounding out supporters of both Sanders and Hillary Clinton, I’m worried that terrible friction is brewing between the two Democratic camps left in this primary.

Democrats all have to unite to win the White House and Supreme Court this year, building bridges without permanent bruising or the confusion of divide-and-conquer.

The state of the race is in flux. Respect and support for Bernie are rising, though Hillary maintains a 212-delegate edge. As of April 3, The New York Times assessed that Bernie will need “landslide” victories in the battles ahead. He’s certain to win more than the 16 states where he has already prevailed. Most of those states have been similar to Wisconsin, where 88 percent of the population is white, an enduring issue for the Sanders campaign. But of the major primaries that are coming up, several might be fruitful territory for Bernie. In New York, Hillary will need to tack towards Bernie on fair-trade issues or face losses in the Rust Belt regions of northern and western New York. Here in California, Bernie trails Hillary by six points, with 7 percent of the electorate undecided. And my sense is that California is winnable for Bernie. Lose or win, Bernie represents the most impressive independent campaign in American history, with the final chapters and legacy yet to be written.

I was an early supporter of Bernie, one of those who thought he could push Hillary to the left, legitimize democratic socialist measures, and leave an indelible mark on our frozen political culture. More deeply, I believed he was the best possible messenger in the wake of Democratic Party shortcomings. As I have argued for years, the liberal failure to create jobs in my Rust Belt heartland, Michigan, for three decades, destroyed hundreds of thousands of lives. Even after the activist explosion against free trade at the Battle of Seattle in 1999, standards of living remained stagnant. It was clear that the next generation would live lesser lives than our parents had. The tuition for a four-year public-university education almost doubled in cost between 2000 and 2015, while student debt rose to 1.2 trillion dollars in 2015. Racial disparities rose with police violence and mass incarceration rates. Michigan, Ohio, and Wisconsin fell to Republican governors, and Congress returned to GOP control.

Like the WTO protests in 1999, Occupy Wall Street “changed the conversation” in America, as the tepid mainstream media phrased it. But we didn’t need a conversation, we needed a change, and soon, in order to save a whole generation.

When Occupy sputtered out, Bernie’s campaign was destined to fill the void. Since winter, the two campaigns have become more visceral, even bitter, fulfilling my fear of a damaging split that could result in lower turnout among Democratic and independent voters this fall, assuming the presidential vote is close. It has become so fractious among Democrats and independents that I began to think that only Trump or Cruz could save us from ourselves. Support for Trump is dropping off now because of his slobbering racism and misogyny, while Cruz represents an even more pompous version of the same. At its core, their appeal is to working-class voters hammered out of their jobs and drawn to economic nationalism, combined with angry resentment of all the social progress achieved from the ’60s until now.

Little is predictable about this election. However, some facts still linger. Without Bernie landslides, Hillary will keep her delegate edge despite Bernie’s overall achievement. If Bernie wins New York and California, each by 1 percent, he still falls short.

Bernie’s army will keep climbing every barricade possible. In his ideal scenario, victories in the final primaries should lead the Democratic superdelegates to shift loyalty from Hillary. Nonetheless, Bernie has received endorsements from only seven House members and none from his current Senate colleagues. No matter how much they agree with Bernie on the issues, no matter what doubts they hold about the Clintons, those running for election or reelection are unlikely to see themselves as benefiting from having a democratic socialist/independent at the top of the ticket.

Hillary is, well, Hillary. I remember seeing her on Yale’s green in 1969, wearing a black armband for peace while a kind of Armageddon shaped up during the Panther 21 trial and Cambodia invasion. Even then, she stood for working within the system rather than taking to the barricades. Similarly, in Chicago 1968, she observed the confrontations at a distance. If she had some sort of revolution in mind, it was evolutionary, step-by-step. In her earlier Wellesley commencement speech, she stated that the “prevailing, acquisitive, and competitive corporate life is not the way of life for us. We’re searching for more immediate, ecstatic, and penetrating modes of living.” But from there it was a determined decades-long uphill climb through those same institutions that had disenchanted the young Hillary.

There are two Hillary Clintons. First, the early feminist, champion of children’s rights, and chair of the Children’s Defense Fund; and second, the Hillary who has grown more hawkish and prone to seeking “win-win” solutions with corporate America. When she seems to tack back towards her roots, it is usually in response to Bernie and new social movements. She hasn’t changed as much as the Democratic Party has, responding to new and resurgent movements demanding Wall Street reform, police and prison reform, immigrant rights and a $15-an-hour minimum wage, fair trade, action on climate change, LGBT rights, and more.

The peace movements from Vietnam to Iraq and Afghanistan, too, are a living legacy that fuels the public majority against sending ground troops into the fiery jaws of war another time. Bernie voted for the war in Afghanistan, but correctly faults Hillary for her hawkish impulse towards regime change. We are likely to live under a what amounts to a war presidency until either a new catastrophe or new movement leads to an alternative to the “Long War” on terrorism.

The populist clarity of Bernie’s proposals can be problematic, even for some of his supporters. For example, to simply reject Obamacare in the belief that “political revolution” will lead to a single-payer solution is simplistic. The path to a Canadian-type system or Medicare for All has fallen short in California and Vermont, and will require Republican defeats this year and in 2018, followed by a presidential showdown in 2020. Meanwhile, Obamacare and the Medicaid expansion are helping 20 million Americans now, mainly youth and people of color, which is a huge improvement that no thoughtful radical can dismiss as merely “reformist.” My friends at National Nurses United are to be congratulated for spending millions supporting Bernie and tirelessly rolling their buses through so many states thus far, but I don’t see a rollout of a Plan B, which requires at least two presidential terms and three more congressional elections. Bernie’s position reinforces the voter impression that his idealism will be blocked in practice. Hillary and Obama’s approach, following on her children’s-health-insurance law, is much easier for voters to understand and support.

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Fracking will be a salient issue in both New York and California, where it has motivated and mobilized thousands of grassroots activists. The anti-fracking movement achieved a historic moratorium on fracking in New York State, where local governments had considerable leverage in a home-rule system. Big names in the entertainment business lent their prestige to the nascent movement, too. Next, the New York model headed to California, amid fracktivists’ confidence that Governor Jerry Brown would either ban the practice or adopt a New York–style ban. I enlisted in the anti-fracking campaign, spending many hours over these three years advocating inside and outside the Brown administration. The movement hasn’t succeeded in California yet, but we’re still committed.

The arguments among environmentalists are the deepest and most frustrating of any I’ve seen for 40 years—but they’re important to understand. Along the way, there have been historic achievements. Our environmental-justice movement, with the leadership of state Senator Kevin De León, wrote into law a requirement that 25 percent of billions in California’s cap-and-trade dollars would go to benefit disadvantaged communities, such as the Central Valley and South Central LA, many of which are predominantly of color. Nearly $300 million began pouring into such communities on a yearly basis. California is spending $120 billion over four years on clean energy, the largest such investment in the country. We also passed the first divestment-from-coal bill in history. Under Brown’s leadership, California created a Global Green Bloc of states and regions, from Canada to China to Europe and Latin America, building a zero-emissions or low-emissions economic powerhouse. A 2014 report found that there are 200,000 clean-energy jobs in the state, surpassing jobs in the fossil-fuels industry.

But the fracking debate continues to leave permanent scars. Despite the governor’s historically high approval ratings, the fracktivists take every media opportunity to thrash him personally. They rack up names on online petitions, but so far have failed to gain political traction. Their apocalyptic view has only worsened. In addition to personally attacking Brown, whose approval rating is 56 percent, they have brutally attacked NRDC and “establishment” environmentalists for not achieving a moratorium in California. Their tactics build their online membership, but turn off or confuse more mainstream Californians.

The Democratic primary may deepen this antagonism and result in defections among Hillary supporters. Hillary wants limits on fracking: a ban where individual states have blocked it, like in New York; safeguards against children’s and family exposures; a ban where releases of methane or contamination of ground water are proven; and full disclosure of the chemicals used in the process. Bernie’s position is that he’s simply against all fracking.

But Hillary’s position goes beyond what virtually any state has done. The New York Times writes that she “has pledged to end subsidies to the fossil fuel industry to pay for her ambitious climate plan” and intends to install 500 million solar collectors in four years. If and when Obama’s Clean Power Plan is upheld in the federal courts, now a likelihood after Justice Scalia’s death, that will bring a even greater change.

Meanwhile, Bernie’s total fracking ban leaves the question of how to do so unaddressed. His energy platform is comprehensive, but he offers no strategy to implement the Paris Summit in the short term. Instead, Bernie will call his own summit of experts in the first hundred days he is president. There is no recognition of the overwhelming wall of opposition from the Republican Congress, which can only be broken on state-by-state organizing. The climate clock is ticking towards doomsday. Where are we moving next, beyond waiting for the overthrow of Citizens United?

For some, like myself (who suffered a serious stroke while investigating fracking sumps in San Joaquin County last year), the question couldn’t be more urgent. I am fully supporting state Senator Ricardo Lara’s legislation setting firm timelines for the phasing out of asthma and cancer-causing emissions of black carbon, methane, and f-gases as an emergency health measure. The bill includes three key deadlines—40 percent methane reductions, 40 percent of hydrofluorocarbon gases, and 50 percent cuts in black-carbon emissions—all by 2030. Emissions of invisible particulate matter are an immediate threat to the lives and safety of millions of California workers, children, and residents of inner and rural towns. The Lara bill is an issue both candidates could immediately unite immediately around.

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My second worry about Bernie’s candidacy is that he has not really faced an all-out Republican-financed media assault in this entire campaign. If he’s the nominee, that will be merciless. And my third concern: Bernie is leading an incredible movement and sowing seeds for the future, but lacks a concrete plan for turning his legacy into a permanent progressive force. We don’t know what will happen to the army of supporters he has assembled, but we already know the pattern of many similar projects—which end up going into decline or divisions.

Voting on June 7 is a personal responsibility for myself and other Californians, just as it is for my friends and colleagues in New York on April 19. What is to be done in this agonizing situation? I still believe a united front against the Republicans is the best and most necessary strategy. But I can’t vote for a united front on June 7.

I intend to vote for Hillary Clinton in the California primary for one fundamental reason. It has to do with race. My life since 1960 has been committed to the causes of African Americans, the Chicano movement, the labor movement, and freedom struggles in Vietnam, Cuba and Latin America. In the environmental movement I start from the premise of environmental justice for the poor and communities of color. My wife is a descendant of the Oglala Sioux, and my whole family is inter-racial.

What would cause me to turn my back on all those people who have shaped who I am? That would be a transgression on my personal code. I have been on too many freedom rides, too many marches, too many jail cells, and far too many gravesites to breach that trust. And I have been so tied to the women’s movement that I cannot imagine scoffing at the chance to vote for a woman president. When I understood that the overwhelming consensus from those communities was for Hillary—for instance the Congressional Black Caucus and Sacramento’s Latino caucus—that was the decisive factor for me. I am gratified with Bernie’s increasing support from these communities of color, though it has appeared to be too little and too late. Bernie’s campaign has had all the money in the world to invest in inner city organizing, starting 18 months ago. He chose to invest resources instead in white-majority regions at the expense of the Deep South and urban North.

Bernie comes from a place that is familiar to me, the New York culture of democratic socialism. From the Port Huron Statement forward, I have believed in the democratic public control of resources and protecting the rights of labor. My intellectual hero is C. Wright Mills, a Marxist who broke with what he condemned as the stale “labor metaphysic” of the communist and socialist parties, embracing instead an international New Left led by young middle-class students around the world. Mills was fresh, honest, and always searching. The 1962 Port Huron Statement declared that we needed liberals for their relevance in achieving reforms, and socialists for their deeper critique of underlying systems. We did not declare ourselves for socialism but for a massive expansion of the New Deal, combined with an attack on the Cold War arms race. We called for a basic realignment of the Democratic Party through the force of social movements, but not through a third party. We even went “part of the way with LBJ” in the face of the 1964 Goldwater threat. From there the Democrats divided over race and Vietnam, eventually leading to Nixon. Even in the ’80s and ’9os, our campaign for “economic democracy” chose not to identify as a socialist movement. With the coming of the 2008 Wall Street crash and Bernie’s campaign, our political culture has changed profoundly in its tolerance of socialist ideas. But is it enough after this truly divisive primary season?

I wish our primary could focus more on ending wars and ending regime change too, issues where Bernie is more dovish and Hillary still harbors an inner hawk. Both Bernie and Hillary call for “destroying” ISIS, whatever that might mean—but it certainly means we are moving into yet another “war presidency.” At least there is strong bipartisan opposition to the open-ended deployment of troops on the ground. But Hillary’s penchant for intervention and regime change can only be thwarted by enough progressive Democrats in Congress and massive protests in the streets and online. Neither candidate so far is calling for the creation of a new peace movement, but that’s the only way to check the drift into another war.

So here we are, at the end of one generation on the left and the rise of another. Both camps in the party will need each other in November—more than either side needs to emerge triumphant in the primary. We still need the organizing of a united front of equals to prevail against the Republicans. It will take a thorough process of conflict resolution to get there, not a unilateral power wielding by the usual operatives. It’s up to all of us.