PHILADELPHIA -- One man in a Bernie Sanders T-shirt stood outside the arena, telling friends how he'd finally snapped at some of his fellow progressive insurgents who kept heckling throughout the first evening of the Democratic convention.

He said he lost his patience when he was jeered for standing to applaud Elizabeth Warren, one of the most progressive members of Congress. He shouted back: "No! I've had to listen to your (crap) all evening."'

Multiple scenes like this played out Monday.

The noisy debate boiled down to a key decision facing Sanders supporters. Now that they've managed to get a hand on the steering wheel of one of the world's most powerful democratic vehicles, do they abandon it and jump out -- or keep trying to guide it?

Bitter arguments broke out among Sanders' army of self-professed political revolutionaries.

"I was thinking, 'Something's going to blow up,"' said Ryan Turner, a delegate for Democrats abroad. "There was actual friction between delegate members... Bernie delegates versus other Bernie delegates.

"It ended becoming shouting matches. I saw security get called. No one got taken away -- but I did hear complaints."

Some Sanders supporters taped their mouths in protest, tore or yanked away Hillary Clinton signs, or kept jeering so often that they wound up being scolded by a fellow Sanders fan, comedian Sarah Silverman, who told them, "You're being ridiculous."

But most didn't respond that way. The loud protests were mainly confined to delegates from a few states.

Most were quiet, or applauded politely.

From his perch up in the last row of the nosebleeds, Haakon Thorsen reflected on what the insurrectionist faction managed to accomplish this year. The North Carolina man had joined as a volunteer, canvassed in several states, and wound up on the national platform committee.

He recalled platform negotiations that ran until one and two o'clock in the morning. In Orlando earlier this month, the Clinton and Sanders sides worked out what many here call the most progressive platform in party history.

The Sanders people got planks for a $15 minimum wage; opposition to the Keystone XL pipeline; free tuition at in-state public colleges; public health care expanded to people 55 and over; and a reinstatement of the old Glass-Steagall Act's limits separating commercial and investment banks.

They didn't get a ban on oil fracking, just possible limits. They fell short on single-payer health care. Same with a carbon tax; they achieved instead a more nebulous commitment to carbon pricing. On the Trans-Pacific Partnership trade deal, Clinton allies held firm against full-fledged opposition: "They said it was going to be offensive to President Obama. We couldn't get everything we wanted."

What they did achieve was a partial takeover of the Democratic party.

One major change spurred by Sanders will see the power of superdelegates severely reduced. In the next election, the weight of party officials in picking a nominee will drop -- likely from the current 15 per cent of delegates, to five per cent.

That means the grassroots will have more clout than it has since the superdelegate system was created in 1984. The system was set up to keep the rank-and-file lefties from putting up candidates like George McGovern -- who'd lost 49 states in a historic slaughter.

Many Sanders supporters wept as their candidate spoke Monday night.

He urged them to continue their political revolution, in the short term by defeating Donald Trump and in the long run by working to elect progressives to everything from schoolboards to national office.

Some of Thorsen's allies have already bailed on the Democrats. They include the intellectual Cornel West, whose work he admired on the platform committee. West now supports the Green party.

"So many of the people I've worked with and canvassed with are like that. There's a good few of them," Thorsen said. "(But) there's many who are coming around and accepting that Hillary is a much better choice, and they may settle for that."

Thorsen is on Team Remain.

In a two-party culture, he said, progressives have their best shot at making a difference through the Democrats. He also worries that special interests would dominate that party again, if his allies all left.

Turner has been a committed Democrat for years and he'll be staying onside too.

As for the people who jeered Monday, he said it's an emotional time: "What we just saw there might be the last time we see Bernie address a large crowd," he said. "That's a lot for people to digest."

Yet he's ready to back Clinton.

"Otherwise, Trump (wins). There's no other way to say it."