The next liberal lion: Bernie Sanders or Elizabeth Warren?

Bernie Sanders and Elizabeth Warren.Associated Press photos/Associated Press

PHILADELPHIA — The progressives in the Democratic Party made their presence known at the convention and throughout the 2016 race. They shifted the party’s platform to the left. They protested outside the Wells Fargo Center and jeered speakers from the convention floor. And thanks to the party’s left flank, Democrats almost nominated a self-described socialist for president.

Now there’s just one question left: Who will be their leader next year, after the new president, whoever that is, moves into the White House?

In one corner, there’s Senator Bernie Sanders of Vermont, who just received 13 million primary votes, had more campaign contributors than anyone else in US history, and is the supporter-anointed leader of a political revolution.

In the other corner is Senator Elizabeth Warren of Massachusetts, who comes armed with PowerPoint presentations and large and lucrative e-mail lists of supporters, and has the power to bridge the gap between Hillary Clinton and the party’s grass roots.

They’ve both taken some hard knocks: Sanders left the convention losing the nomination, and Warren exited without making the national ticket as the vice presidential nominee.

But their influence over the convention and the presidential race shows how Democrats have moved to the political left in recent years. The convention, specifically, might also preview the country’s next liberal leader, who will serve as a check on the next president, no matter the party.

“There is no question that Senator Sanders has laid claim to that mantle,” said Georgetown University professor Michael Eric Dyson, a Clinton supporter since the spring. “He is leading a movement, and he has earned it.”

Steve Grossman, a former Democratic National Committee chairman and Massachusetts treasurer, said that it will likely be a combination of both.

“I think you need Warren and Sanders in the United States Senate as the co-leaders of the progressive moment to push the president relentlessly in a progressive direction,” Grossman said.

But tactically, Democrats said, neither Warren nor Sanders has the deep relationships inside the Senate or with outside progressive groups like the Senate’s last liberal lion, Ted Kennedy of Massachusetts, did.

“It isn’t just having a mass following, it is also having credibility with organized groups that when a leader says we are going to do this particular cause at the moment, everyone follows,” said David Nexon, a former Kennedy staffer who coauthored “Lion of the Senate: When Ted Kennedy Rallied the Democrats in a GOP Congress.”

“Kennedy was able to be that person,” Nexon said. “I think Warren and Sanders have the capacity to do it, but I am not sure it is fully developed.”

Longtime Senator Patrick Leahy of Vermont said the Senate also has more unabashed liberals than when Kennedy was a leader there in the 1990s and 2000s.

“What Ted did is step back and include people, and whoever wants to lead us progressives now — whether it be Warren or Sanders — needs to include people,” said Leahy, a Democrat. “Loners don’t make it. Teddy made it because he would form coalitions.”

Coalition building is where Sanders and Warren could find their own lanes. Warren could focus on the inside via policy-making in the Senate, while Sanders could work on the outside to leverage his campaign of activists around the country.

On Wednesday morning, after he officially suspended his presidential campaign on the convention floor, Sanders told Rhode Island delegates that he intends to use his political capital outside of the Senate.

“Our campaign is now transitioning from a campaign trying to elect a president, to a campaign that is now trying to really develop a grass-roots movement to bring more people into the process,” Sanders said.

That said, should Democrats retake the Senate majority this year, Sanders could be in line to chair the Health, Education, Labor and Pensions Committee — just as Kennedy did several years ago.

There’s also a matter of timing. Warren, 67, is serving her first term and could still run for president. Sanders, 74, has likely run his last national campaign and may be more motivated to hand the torch to someone else.

“The truth is that there is no need for them to clash over a leadership role because they can lead in different areas doing different things,” said Charles Chamberlain, the executive director of the progressive Democracy for America in Vermont, who organized a Draft Warren for president effort before eventually endorsing Sanders in the primary. “Sanders has a full range of issues he has talked about in the campaign, while Warren is laser focused on income inequality and Wall Street reform.”

Instead of one lion, there could be “many lions,” said Progressive Change Campaign Committee cofounder Stephanie Taylor, adding, “Let many flowers bloom.”

It’s also possible that progressive leadership — at least on some issues — could come from the White House if Clinton is elected. For example, the progressive agenda is increasingly driven by movements like Black Lives Matter.