PHILADELPHIA – Elite Democrats were alarmed at the start of the Democratic National Convention on Monday, when rowdy Bernie Sanders delegates kept up storms of booing whenever Hillary Clinton's name was mentioned. Given that the entire point of the convention is to slather the party's nominee with worshipful adoration, the pro-Bernie hubbub was reportedly harshing the mellow of senior party officials.

But as the convention progressed, and America's leading lefties all lined up to endorse voting for Clinton as the best move in November, the protests grudgingly died down to a handful of people who occasionally set up some booing or chanting — even interrupting Sanders himself a few times.

Such people were a tiny minority in the convention hall, however. Sanders was greeted with rapturous, almost delirious cheering that went on for several minutes when he came on stage. And while Clinton is the nominee, Sanders' strategy of trying to change the party from the inside is going better than even he could have imagined two years ago.

Here's the basic logic of running an insurgent campaign for a party nomination: You see how high you can run up your vote total, and depending on how close you made the race, you leverage that support for some concessions in the party platform and from the winner. In return, you endorse the winner and set the stage for the next campaign attempt.

Sanders got reasonably close to winning outright, an astonishing result that undoubtedly has more mainstream Democrats like Elizabeth Warren or Kirsten Gillibrand kicking themselves for not grokking Clinton's electoral weakness. As a result, Sanders' people got some important concessions, like support for a public option for ObamaCare, a $15 minimum wage, and Medicare buy-in at 55. It's not everything they wanted, but those and other Sanders-backed planks in the party platform would be tremendous policy improvements.

In return, he delivered the promised endorsement, with a deft speech that acknowledged the ideological abyss between himself and Clinton, but laid a convincing case that voting for her was the best move for the moment. Clinton supporters, exhausted like everyone at this grinding death march of an election, cheered wildly when he spoke positively of the party nominee. Most everyone in the conventional hall welcomed a break to intra-left squabbling.

Most Sanders supporters at the convention seemed to endorse the basic logic here, embodied by a hand-drawn sign that read "BERNIE THEN, HILLARY NOW, TRUMP NEVER." Susan King, a 29-year-old Sanders supporter visiting from Boston, told The Week that while she was no fan of Clinton, it was time to bury the hatchet, for now: "With Trump, you basically have to vote for Clinton, at least if you live in a swing state." Nationally, polls show that some 90 percent of Sanders voters plan to support Clinton in the general election.

There is, of course, a loud minority of Sanders supporters who feel betrayed by Warren and their own candidate. He has activated a large number of people who haven't participated in electoral politics before, as well as several ideological factions that had previously abandoned such practices, and the experience of defeat is stinging. Some left-wingers, seemingly almost relieved at returning to their traditional stance of powerless outsider, now denounce Sanders as a traitor. "We trusted you!" a few people yelled at Warren during her speech.

But again, the endorsement of Clinton is part and parcel of attempting to change the Democratic Party from the inside. The fact that Sanders, a relative nobody with almost no powerful allies in the party, got as far as he did, suggests that the next challenge attempting to force social-democratic policy on the recalcitrant Democratic elite is going to succeed.

The ancient and rickety United States constitutional system is not very friendly to left-wing radicals. But it is not completely closed either. The next generation of Sanders Democrats is going to far surpass his high-water mark.