Anger at the political establishment has overtaken the Republican presidential race, embodied in the candidacy of Donald Trump. But it is also coursing through the Democratic electorate, fueling the popularity of Bernie Sanders, inspiring liberal challenges to party-backed congressional candidates and spurring activism on causes from the minimum wage to the Keystone XL oil pipeline.

Nowhere was the discontent on the left — which has made targets out of banks, billionaires and backers of the status quo — more evident than in the stunning news last week that Sanders, who calls himself a democratic socialist, was raising money nearly as fast as Hillary Rodham Clinton.

Interviews with three dozen Democrats in key early states — a mix of undecided voters and Sanders and Clinton supporters — laid bare a sense of hopelessness that their leaders had answers to problems like income inequality and gun violence. It is frustration that Sanders, a senator from Vermont, and other progressive candidates are channeling and that Clinton has addressed with increasing passion, as when she responded to Thursday’s massacre at an Oregon college by saying she was "just sick of this."

While alienation among Republicans has drawn more attention, given the fiery language of the race’s front-running celebrity, Trump, the anti-establishment mood on the left is just as intense and potentially just as consequential to the selection of a Democratic nominee.

Clinton has tried to lift her declining poll numbers by highlighting endorsements from governors and lawmakers — but such establishment backing has yet to do much good. Vice President Joe Biden could face the same anti-establishment headwinds if he enters the race, given his four decades in Washington, although allies believe he has the personal touch to win over angry Democrats. Sanders castigates "the entire political and economic establishment" regularly, by contrast, a message that has drawn 650,000 donors and huge crowds of fervent supporters, like the 20,000 people at his Boston rally on Saturday evening.

"I volunteered for Hillary when she ran for president in 2008, but her time is past, I think," said Nikky Raney, 25, a Democrat from Dover, New Hampshire. "And it’s Bernie who seems most genuine about universal health care and getting big money out of politics."

Though Clinton remains popular in the party, especially among those who want to see a first female president, Sanders’s call for a "political revolution" and his consistently left-wing policy ideas are inspiring to younger voters, seniors and liberals who would prefer to see a true believer overcome an establishment goliath.

"Income inequality has been growing for so many years that a lot of young people feel their Democratic leaders aren’t fighting hard enough on the issue," said Brandon Lemay, the president of the Plymouth State University Democrats, after attending a speech by Clinton near the campus in central New Hampshire.

Lemay said he was undecided between her and Sanders. "Hillary has definitely been refining her message to sound more liberal," he said, "but Bernie’s convictions are just very strong, very intense."

The disaffection among Democrats flows mainly from three sources, according to interviews with voters and strategists. Disappointment lingers with President Barack Obama over the failure to break up big banks after the Great Recession and fight for single-payer health insurance, among other liberal causes. Fatigue with Clinton’s controversies endures, as does distaste with her connections to the rich. And anger abounds at party leaders for not pursuing an ideologically pure, economically populist agenda.

"Establishment Democrats like Hillary could end up heavily outspending people like Sanders, but it may not matter as much as usual because voters are searching for someone off the beaten path," said Paul Maslin, who was the pollster for Howard Dean’s 2004 presidential race.

Tom Henderson, the Democratic chairman in Polk County, Iowa, which includes Des Moines, said the most widely shared frustration among Democrats there was "the manner in which the economy has bounced back" under Obama: Wall Street returns look strong and unemployment has declined, but wages and benefits are largely unchanged.

"I think Sanders is pulling in voters who aren’t typical rank-and-file Democrats, but rather folks who have become energized over the last few years to change the country’s direction," said Henderson, who is currently neutral in the race. "The question for Sanders is whether he can get those people to show up and vote in February."!~neIP~!

Across the country, discontent on the left is bubbling up in scattered ways.

Liberal activists in Iowa and elsewhere have pushed local Democratic officials to enact minimum-wage ordinances in the face of inaction from state and federal government officials in both parties. Environmentalists put enormous pressure on Clinton to come out against the Keystone pipeline project, which she did last month. Many progressives in New York City complain that the Democratic mayor, Bill de Blasio, appears to have lost his appetite for a criminal justice overhaul.

And last week, about 80 Democrats in New Hampshire banded together to demand that the Democratic National Committee allow candidates to participate in more debates than the six that the party has sanctioned. Many activists see the limit as rigging the debates in favor of Clinton, whose advisers wanted as few as possible.

"There’s a level of anger among Democrats that the establishment has decided not to address, whether it’s about debates or other issues," said Peter Burling, a former New Hampshire state senator who is supporting former Gov. Martin O’Malley of Maryland in the presidential primary.

If Sanders proves too liberal to capture the nomination, allies of Biden believe the vice president is positioned to seize on anger at the establishment if he enters the race — even though his long tenure epitomizes it. These supporters say the freely emotional Biden is more capable of soothing Democratic anxieties than Sanders, a flinty Vermonter, or Clinton, whose attempts to appear more likable and funny can come across as overly calculated.

Still, Biden has not decided on a run, and "Draft Biden" efforts have not yet caught on anywhere near the way Sanders has.

"There’s just so much hopelessness about people having any real opportunity to just make a living, take care of their families, support themselves," said Karen Bryant, a physician from New Boston, New Hampshire. "Mrs. Clinton is floundering and Republicans like Jeb Bush are floundering because people see them as politicians whose messages change depending on who they are talking to or how much money they need to raise. If you live year after year not seeing politicians keep their promises, it leads you to support someone like Bernie Sanders."