"Secretary Clinton has won the Democratic nominating process, and I congratulate her for that,” Sanders said to a crowd in Portsmouth. "She will be the Democratic nominee for president and I intend to do everything I can to make certain she will be the next president of the United States."
The Democratic Party will now move quickly to bring Sanders' supporters into the fold in an effort to defeat Donald Trump next year, focusing on swing states including Ohio, Florida, and Pennsylvania as well as progressive grassroots groups. Already the Clinton campaign has sent aides to win over Sanders' networks, preparing for what is set to be the most acrimonious general election in at least a generation.
The Vermont senator’s support for Clinton comes after weeks of back-room wrangling over the Democratic Party’s platform in which Sanders won a slew of concessions, creating what both sides have called the most progressive Democratic agenda in recent history.
"Our job now is to see that platform implemented by a Democratically controlled Senate, a Democratically controlled House and a Hillary Clinton presidency," Sanders said, vowing to help Clinton campaign for president in the coming months. "And I intend to be in every corner of this country to make certain that happens."
Sanders' endorsement for Clinton is a long time coming. While the two appeared in the Democratic primary to share many of the same broader goals, they disagreed, often virulently, on policy details from healthcare-for-all to college tuition. Sanders contested the primary to the bitter end in Washington DC, despite having little chance of winning after a series of defeats in March.
After the primaries ended, Sanders and Clinton's campaigns negotiated for weeks over the Democratic Party platform.
The Vermont senator refused to endorse his opponent in an attempt to force a more liberal agenda for the Party, successfully winning calls for a $15 minimum wage, breaking up too-big-to-fail banks, a tax on carbon, near-universal free college and other measures. Finally on Tuesday, the two parties met in New Hampshire and endorsed a joint agenda.
"These aren't just my fights, these are Bernie's fights," Clinton told the audience after Sanders had spoken. "He has energized and inspired a generation of young people who care deeply about our country and are building a movement that is bigger than one candidate and one campaign."
Still, there is lingering resentment against Hillary Clinton and the Democratic Party. Some Sanders supporters believe the primary was stolen through election fraud, though there is little widespread evidence of that. (Sanders lost by about 3 million votes.) Many distrust Clinton and took to social media to express their anger at Sanders' endorsement.
"I'm sorry to see that you've endorsed corruption for President," said one Facebook commenter on Sanders' page. "You are dead to me now," said another.
Yet most Sanders supporters have jumped on board Clinton's campaign: 85% support her, according to a new Pew poll, compared with 69% of Clinton supporters who backed then-Sen. Obama at this point eight years ago.
Democracy for America, the grassroots liberal group that helped fuel support for Sanders, said on Tuesday it was endorsing Clinton. “ We're backing Hillary Clinton in the race for President because she gives our country the opportunity to smash one of its last great glass ceilings and will be the partner we need in the White House to realize the agenda that Bernie Sanders's political revolution fought for in the primaries -- from tuition-free college to Social Security expansion," Charles Chamberlain, DFA's executive director said.
Sanders covered many of his usual stump speech themes on Tuesday, except that he inserted Hillary Clinton's name throughout. "Hillary Clinton understands that we must fix an economy in America that is rigged and that sends almost all new wealth and income to the top one percent," Sanders said. "Hillary Clinton understands that if someone in America works 40 hours a week, that person should not be living in poverty."
Clinton, meanwhile, called for many of the progressive ideas that both she and Sanders endorsed during the primary: creating new infrastructure jobs, overhauling the campaign finance system, combatting climate change and reforming the tax code.
In both their speeches, however, each adopted much of the language the other has used throughout their campaigns. "We need to go big and we need to go bold. This isn't a time for half measures," Clinton said, calling for an economy that works "for everyone," not just "the millionaires and billionaires"—a familiar Sanders refrain.
And Sanders for his part said that Americans "become stronger when black and white, Latino, Asian American, Native American – all of us – stand together." "Stronger Together" is Clinton's campaign slogan. And he rehashed Clinton's older slogan, "I'm with her," when he ended his speech.
"Hillary Clinton will make an outstanding president and I am proud to stand with her here today," Sanders said.