But while Sanders is now officially on the Clinton train, some of his supporters are refusing to join him.
Even after the joint event, where Clinton and Sanders declared war on Donald Trump and praised each others' political careers and policies, some voters who supported Sanders during the Democratic primary simply said this about Clinton: "Never Hillary." The skepticism -- and even animosity -- that some here expressed is a clear sign of the work Clinton will have to do to win over populist liberals in the months to come.
Sam Weaver, 24, of Webster, Massachusetts, said there was nothing Clinton could say or do to win his support -- and that he wasn't yet convinced Sanders could not emerge the Democratic nominee.
"If he gets the nomination, then we'll run with it all the way to November," Weaver said.
Weaver added that he does not want Trump to win the White House. But asked whether he worries he would be helping Trump by supporting Green Party candidate Jill Stein or writing in Sanders in November, Weaver shrugged, saying he believes there are ways for Congress to "restrict" Trump's power.
"Anything but Hillary," said Will, 23, from Salem, Massachusetts.
"I don't believe that someone who five days ago was being hounded by the FBI is someone I would trust with my future," he said, a reference to the investigation into Clinton's use of a personal email server during her tenure at the State Department. The FBI concluded after an investigation that it would not recommend criminal charges against Clinton, though its director, James Comey, said the probe had shown Clinton and others had been "careless."
For her part, Clinton addressed Sanders' supporters directly
in her speech Tuesday, acknowledging that her former rival's campaign had begun a political revolution.
"Sen. Sanders has brought people off the sidelines and into the political process. He has energized and inspired a generation of young people who care deeply about our country," she said. "To everyone here and everyone across the country who poured your heart and soul into Sen. Sanders' campaign: Thank you."
Her campaign also created a $27 donation button on its website, a nod to the average donation Sanders received during his primary run fueled by small donors that became a calling card of his effort.
Kathy Bouchard said her inability to support Clinton had everything to do with trust.
"She has not won my trust," said Bouchard, a 56-year-old woman from Maine who is unemployed. "She may be saying these things to win over Bernie Sanders' supporters but I just don't quite believe it."
The only scenario in which Bouchard could imagine herself voting for Clinton is if the former secretary of state chose Sanders as her running mate.
Bouchard's friend, Seth Berner, chimed in that he would "likely"' support Clinton in November -- but only because he viewed Trump as the worse of two evils.
"If she's talking about those kinds of issues now," Berner said, referring to issues important to working and middle class and unemployed Americans, "it's only because she was starting to lose primaries and caucuses to things that Bernie has been saying."
Asked what he thought of Clinton's speech, Berner said: "I didn't hear her speech. I left after Bernie's."