Back in May, establishment reporters were writing obituaries for the left's attempt to take over the Democratic Party. Alex Thompson wrote at Politico that the left was in "despair," thanks to Joe Biden defeating Bernie Sanders, and the failure of three other progressive primary challengers. Conservative columnist Josh Kraushaar at National Journal confidently predicted the "end of Alexandria Ocasio-Cortez's revolution," as three members of the "Squad," including AOC herself, were facing their own primary challenges.

Now it's August and, with several more rounds of primaries gone past, a good time to take stock. Democratic socialists AOC and Rep. Rashida Tlaib (D-Mich.) obliterated their primary challengers easily. Progressive Mondaire Jones won an open primary in New York, Jamaal Bowman defeated longtime incumbent and chair of the House Foreign Affairs Committee Rep. Eliot Engel (D-N.Y.), and Black Lives Matter activist Cori Bush ousted the moderate incumbent Rep. William Lacy Clay in St. Louis. Leftist candidates have also made strides at the state and local levels in New York, Texas, Pennsylvania, and elsewhere.

It seems predictions of the left's demise were somewhat premature. This year's fight is not over — Rep. Ilhan Omar (D-Minn.) has her own primary in a few days, among others — but it is clear that the movement Bernie Sanders helped build will outlast him.

Left-wing politics is a challenge in any country, and especially so in the United States. The basic goal of the left is equality, which necessarily means displacing rich elites from their control over the economy and the political system. Money buys political influence, in the form of campaign contributions, control of the media, bribery, and so forth. And if that doesn't work, there is always outright oppression. Nascent American socialist and union movements have indeed been repeatedly strangled by naked political repression, from legal harassment, to frenzied witch-hunts, to assassination and mass murder. For all the operatic whining about "cancel culture" from the right these days, I would much rather be dragged online than thrown in prison for criticizing a stupid war, or shot to death by the national guard for going on strike.

So far we have not yet seen that much illiberal repression or terrorist violence directed against the modern left (though there has been some). But the Democratic Party establishment still has considerable advantages. They have a deep-pocketed donor class, broad support among the mainstream press, and probably most important, an increasingly unhinged and extreme Republican Party. The most effective argument moderate Democrats have used against the left is simply pointing at the GOP and saying "we can't take the risk." Somehow it still worked in 2020 even after a moderate Democrat lost a gimme election to a reality TV clown in 2016.

That said, the left has largely won the argument about values among Democratic voters. A Pew poll from this January found 61 percent of Democrats and Democratic-leaning registered voters think the government should provide more assistance to the needy, 72 percent support tuition-free college, and 74 percent support Medicare-for-all. Fully 95 percent think economic inequality is a big problem, and 85 percent think corporations have too much power.

Now, as the unfortunate defeat of Sanders shows, agreement does not automatically translate to support. One has to undertake a grinding process of mobilization and argument to convince the Democratic base to emerge from its defensive crouch and to start actually demanding the things they believe in. The original Black Lives Matter protests in 2014 and the Sanders campaign in 2016 got the ball rolling, and the George Floyd protests accelerated things dramatically. Both Bowman and Bush gained enormous attention and support thanks to their association with the movement and the intense coverage of racial injustice. Left-wing challenges have generally performed best when tied directly into the movement for racial injustice, particularly when they involve candidates of color.

There will no doubt be many more reverses in the future, and overall success is by no means guaranteed. This kind of political effort is always a patchwork, herky-jerky process, with candidates winning here and losing there — but the general trend is undeniably up. In 2021 there will be the beginnings of a socialist caucus in the U.S. Congress for the first time in American history. The moderate congressional leadership has managed to cling to power so far, but they are all 69 years old or older, and the left has proved that even committee chairs are no longer safe. Without another paroxysm of repression, it will be harder and harder for moderate Democrats to excuse their hesitation and timidity.

They had better keep one eye over their shoulders. The left's long march through the Democratic Party has only just begun.