California law allows the parties to limit participation in what will be the last major primary in June. For 2016, however, the California Democrats decided to open up their election, while the Republicans are keeping theirs closed. That could prove to be a fateful decision if the Democratic battle is still undecided. Some of the anti-establishment, independent vote that might have gone into the Republican primary could go to Sanders (also a possibility in other open-primary states now that Rand Paul has dropped out).

Party opposition to Sanders is especially strong among Democratic officeholders. In FiveThirtyEight’s endorsement primary, Clinton has a lead over Sanders of 466 to 2. Although endorsements themselves may not matter much in swaying voters, they’re an indication of the depth of party support, which will likely translate into a substantial edge for Clinton among the 712 superdelegates at the Democratic convention unless she stumbles badly in the primaries.

Sanders and his supporters see the party support for Clinton as evidence that “the establishment” is against him. But there are two other interpretations. What party leaders necessarily care about is winning the next election. They look at the electability of the presidential candidate as it affects the electoral prospects of candidates at all levels, including their own. The endorsement primary is a symptom of deep anxiety about what Sanders would do to the entire party’s fortunes in November.

The lack of support for Sanders among elected Democrats may also reflect his lack of support for them. During 2015, Clinton raised $18 million for other Democratic candidates, while Sanders did no fundraising for them at all. Those are just last year’s numbers. The difference in party fundraising between them going back decades would surely be even more dramatic. After all, before this campaign began, Sanders was emphatic that he was not a Democrat.

Sanders has left a long trail of denunciations of the Democratic Party. He began on the revolutionary left; in 1980, he served as an elector for the Socialist Workers’ Party, founded by Leon Trotsky and committed to nationalizing major industries. In 1989 he said the Democrats and Republicans were “in reality, one party—the party of the ruling class.” That year he wrote an op-ed in the New York Times describing the two parties as “tweedle-dee” and “tweedle-dum” since both subscribed to what he called an “ideology of greed and vulgarity.” As the Republican Party has moved to the right, Sanders has said the Democrats are better, but he has refused to run as a Democrat and continued to insist—as late as the 2012 election—that he is not a Democrat because the party fails to support the interests of workers.

Though he refers to “Wall Street” and “big corporations” in his current campaign rather than to “the ruling class,” his attacks on Democrats are basically the same as before. They’re just focused on Clinton now. But what he says about her he could just as easily say about most Democrats running for Congress or in the states—and they surely know it.