For evidence of the growing divide between the Democratic Party’s conservatively minded leadership and its progressive-oriented base, look no further than the recent party convention in California.

Probably anticipating a degree of polite deference, two presidential candidates made separate attempts to lecture the assembled 4,500 delegates about the perils of pursuing a transformative agenda — and were met with resounding and audible boos from the crowd.

Using his appearance to issue an all-too-familiar (and incorrect) denunciation of Medicare for All, former Maryland congressman John Delaney declared:

What we need as Democrats is to build an economy that works. But it’s got to be with smart policies. Medicare for All may sound good, but it’s actually not good policy nor is it good politics. I’m telling you…

Spluttering while the room reacted poorly, Delaney then awkwardly tried to deliver a defense of private health insurance while wagging a finger at the crowd.

John Hickenlooper’s speech somehow proved even more awkward, with the former Colorado governor drawing angry boos as he attempted to denounce socialism:

If we want to beat Donald Trump and achieve big progressive goals, socialism is not the answer… We shouldn’t try to achieve universal coverage by removing private insurance from over 150 million Americans. We should not try to tackle climate change by guaranteeing every American a government job.

Predictability, the booing drew swift condemnation from a chorus of agitated blue checkmarks — among them Jim Kessler, the cofounder of centrist think tank Third Way; and Mark McKinnon, cofounder of the self-satirizing No Labels initiative.

“When the primaries are all said and done,” pronounced Kessler, “the California Dem Party convention’s booing of @Hickenlooper for criticizing socialism may be remembered as a seminal moment. Good for #hickenlooper.”

According to McKinnon: “John @Hickenlooper just had a Bill Clinton Sister Souljah moment. Sometimes speaking hard truths and saying what is unpopular to the extremes of the party is the right medicine. And good politics.”

While it would be excessively optimistic to interpret the crowd’s reaction as evidence of a major socialist tendency within the California Democratic Party, it’s certainly encouraging that so many delegates seemed irked by Delaney and Hickenlooper’s respective sermons.

Consciously or not, both belong to a longstanding tradition, in America and elsewhere, in which politicians of the nominal center-left have tried to score points by talking down to their own activist base. Call it the liberalism of triangulation: from Bill Clinton to Tony Blair, the first generation of neoliberal politicians made tacit and sometimes overt jabs at their traditional bases a regular part of the political arsenal.

Clinton did it in Arkansas by picking fights with teachers unions (despite having previously courted their support), Blair by distancing himself from the Labour Party’s social-democratic past and insinuating that its leading figures and values were relics of a bygone era. Both men presented themselves as “modernizers” (Blair even called himself a “radical”), bringing their parties into sync with political reality by rejecting old dogmas and ideological purity.

The logic of these strategies was simple: by borrowing ideas and rhetoric from the Right and attacking elements within their own traditional bases of support, neoliberal politicians hoped to secure an electoral monopoly. And besides, as this cynical line of reasoning went, where else were activists and constituencies like the labor movement going to go? Such tactics were propelled in part by a media environment increasingly hostile to the traditional left and wedded to neoliberal ideas about politics, markets, and the welfare state.

To this day, center-left politicians who reject left-wing policies or repudiate traditional left-wing values effortlessly earn friendly labels like “moderate” and “pragmatic.” Cable news loves a Democrat who will drone on about deficit reduction and has the courage to manage their own supporters’ expectations downward by invoking language pioneered on the Right.

Currently polling around 1 percent in the crowded Democratic field, Hickenlooper soon after told CNN: “We had no illusions that everyone was going to embrace the message. We thought it was important to say, right? Not everyone in the party is going to rally to that perception, but I feel that it needed to be said.”

For committed centrists like Kessler and McKinnon, the former governor’s poorly received remarks were therefore an act of political courage: the preaching of uncomfortable truths; the administering of, in the latter’s words, “the right medicine.”

But there’s nothing bold or courageous about deferring to the wishes of corporate interests over rank-and-file voters. Medicare for All’s greatest opponents are lobbyists and insurance industry shareholders who stand to lose billions in profit in the event of its success. That opposition is certainly a political reality, but it’s hardly an objective or neutral one. Accepting it as intractable and rejecting Medicare for All is, similarly a political choice — and a cowardly one at that.

Whatever its pretenses to hard-headed realism, Big Centrism is ultimately an astroturfed compromise between corporate America and political elites, not a hard-headed electoral strategy rooted in objective realities. (No Labels, McKinnon’s outfit, incidentally counts hedge fund and private equity barons among its donors, while Third Way has received tens of thousands from Big Pharma.)

While there’s still a long way to go to break its grip on the nominal left of American politics, the liberalism of triangulation is finally showing real signs of decay — and the California Democratic Party convention is proof.