In recent months, Bernie Sanders has transformed Dennis Brandau from a guy who hated politics into a first-time voter. On Tuesday, the 29-year-old line cook will proudly cast a ballot for the Vermont senator in Pennsylvania's Democratic presidential primary.
But the bruising campaign this year also has turned Brandau into a fierce opponent of the Democratic front-runner, former Secretary of State Hillary Clinton. He says he has a hard time imagining backing her this fall if she wins the nomination.
"I don't know if I can vote for her," Brandau said. "I don't even want to hear her talk."
Sanders' chances of winning the nomination have dimmed since his 16-point loss to Clinton in last week's New York primary. Polls show he faces an uphill race in several of the five Eastern states that vote on Tuesday, as well as in California's June 7 primary.
Some of his supporters remain so steadfast, however, that a #BernieOrBust movement has picked up momentum on Twitter. So has an online pledge for supporters who vow to vote for Sanders as a write-in candidate if he loses the nomination.
A recent McClatchy-Marist poll found that 1 in 4 Sanders supporters would not back Clinton as the nominee, a sign of the party's deep divide — and Clinton's high negatives — at this point of the race.
Democratic pollster Anna Greenberg says she is confident that many Sanders supporters will ultimately vote for Clinton if she wins the nomination, especially if she faces Republican front-runner Donald Trump or Texas Sen. Ted Cruz.
"They might have to hold their noses to vote for her, but she's going to seem better ... than the alternative," Greenberg said.
Sanders has pledged to back Clinton if she is the nominee, and has spoken often of the necessity of defeating Trump.
At a rally Saturday in Baltimore, he was introduced by civil rights leader Benjamin Jealous, who told a crowded downtown arena: "Our No. 1 purpose in this election must be to defeat Donald Trump."
Sanders appeared to ease some of his harsher attacks on Clinton, focusing instead on their different positions. He criticized her support of free-trade deals, her super PAC spending and her refusal to release transcripts of paid speeches she gave to Wall Street firms while she was out of office. The large crowd responded with loud boos.
In interviews, Sanders has said he has no intention of being another Ralph Nader — the third-party candidate blamed by many Democrats for siphoning votes from Democratic nominee Al Gore in 2000, helping give the White House to George W. Bush.
"In the heat of the campaign things look intense, but eventually everybody comes together," said Democratic strategist Bill Carrick.
Tensions were just as high in 2008 when Sen. Barack Obama beat Clinton for the nomination, he noted, but Clinton ultimately endorsed Obama and campaigned for him.
Anne Sabin, an accountant who heard Sanders speak in the Philadelphia suburb of Oaks, says he opened her eyes to the need for campaign finance reform.
She hopes Sanders "crushes" Clinton and gets the nomination, she said. "But if he doesn't, I'll vote for Hillary, holding my nose while I pull the lever."
Early in the race, Sanders drew applause in a debate by telling Clinton that he was "sick and tired of hearing about [her] damn emails," declining to join Republicans in attacking her for using a private email server while she was secretary of State.
But after his insurgent campaign caught fire he hammered her on other issues, saying at one point that he didn't think she was qualified to be president, a charge he later withdrew. But as vitriol grew on both sides, he stopped urging supporters to stop booing Clinton at his rallies.
Although Clinton and Sanders agree broadly on many policies that Republicans oppose, such as raising the minimum wage and letting people who are in the country illegally stay here, the longtime political independent has portrayed her as a political insider beholden to special interests. That image will be hard to shake.
"I'm not going to vote for Hillary Clinton," said Hugh Espey, executive director of the Iowa Citizens for Community Improvement Action Fund, a community organizing group backing Sanders. "She's a part of the rigged political system."
While Espey believes Sanders has forced Clinton to the left on some issues, noting her opposition to the proposed Trans-Pacific Partnership trade deal, he doesn't trust her to keep those promises in office, and doesn't believe she will stand up to Wall Street.
His group, which is working to raise the minimum wage in Iowa, is one of many organizations trying to capitalize on the enthusiasm surrounding the Sanders campaign to build support for other causes.
"This is a movement moment," Espey said. "What we're doing is building the political revolution Bernie's talking about."
Sanders often speaks not just of winning the presidency, but of starting a "political revolution."
His rallies often feel more like festivals than political events, with fans selling homemade T-shirts and candles and local bands sometimes kicking off his speeches. Millions of individuals have contributed money to help him keep pace with Clinton's fundraising operation.
RoseAnn DeMoro, executive director of National Nurses United, which is backing Sanders, says if Clinton wins the nomination she'll have a messaging problem in the fall election.
"Saying 'I'm not Trump' is not the most inspiring message," DeMoro said. "People might vote for her, but they won't work for her."
Alex Vader, 24, agrees. In recent weeks, she and her boyfriend have hit the pavement for Sanders near Philadelphia.
"We were out in the snow and rain for Bernie," said Vader, an engineering student. "I wouldn't do that for Hillary. She doesn't inspire me that much."
Corty Byron, 30, a musician who opened up the Sanders rally Saturday at a gym in Millersville with Woody Guthrie's "This Land is Your Land," said he would willingly support Clinton in the fall.
A guitarist in the band has vowed to write in Sanders' name in November if he isn't on the ballot.
Byron says that he is terrified of Trump winning, and that Sanders has had an impact just by running and it would be a mistake for liberal voters not to vote for Clinton on principle.
"The loud voice has been heard," Byron said. "That's what's most important."