Bernie Sanders has urged Democrats to put Hillary Clinton in the White House, in a speech to the party convention.
The Vermont senator received a three-minute standing ovation when he took the stage in Philadelphia.
“Hillary Clinton must become the next president of the United States,” he said as the crowd erupted in cheers.
First Lady Michelle Obama also received a rapturous reception for a powerful speech in which she took on Republican nominee Donald Trump.
“Don’t let anyone ever tell you that this country isn’t great, that somehow we need to make it great again. Because this, right now, is the greatest country on earth.”
Earlier in the evening, Mr Sanders’ fans had booed any mention of Mrs Clinton, who will accept the party’s presidential nomination on Thursday.
And as he implored them to back his Democratic rival in the final major speech of the night, they held aloft their blue “Bernie” signs and chanted his name.
Some supporters broke into tears while others wore duct tape emblazoned with the words “silenced” over their mouths.
“While Donald Trump is busy insulting one group after another, Hillary Clinton understands that our diversity is one of our greatest strengths,” Mr Sanders continued.
“If you don’t believe this election is important, if you think you can sit it out, take a moment to think about the Supreme Court justices that Donald Trump would nominate and what that would mean to civil liberties, equal rights and the future of our country,” he said.
In other highlights on Monday:
- Mrs Obama took on Mr Trump, saying: “When someone is cruel or acts like a bully, we don’t stoop to their level.”
- Senator Elizabeth Warren attacked the business record of Mr Trump
- Comedian Sarah Silverman, who supported Mr Sanders, told his supporters to get behind Mrs Clinton
- One of the loudest cheers went to Senator Cory Booker when he told the crowd: “In America, love always trumps hate”
Members of the audience had earlier disrupted the event’s opening prayer, chanting “Bernie!” while also jeering as Democratic National Committee chair Marcia Fudge delivered remarks.
The commotion prompted Mr Sanders to send an email saying the credibility of the progressive movement would be damaged by “booing, turning of backs, walking out or other similar displays” of protests.
Revelations from an email leak which showed DNC officials allegedly plotted against Mr Sanders’ primary campaign threatened to overshadow the event as it fuelled the anger of his voters.
Wikileaks released emails that revealed the DNC was biased against Mr Sanders when he ran against Mrs Clinton in the hard-fought primary contest.
The FBI has confirmed that it is investigating the leak.
Chairwoman Debbie Wasserman Schultz resigned on Sunday as pressure built on the party to address the scandal.
Democratic party bosses later issued an apology to Mr Sanders for “inexcusable” emails which tried to undermine his White House campaign.
But Mr Sanders refused to let the email scandal eclipse his message to his supporters.
“Hillary Clinton will make an outstanding president and I am proud to stand with her here tonight,” he said before he left the stage.
About 5,000 party delegates are among the 50,000 people expected to attend the four-day convention, which will end on Thursday with Mrs Clinton formally accepting the nomination for president.
1. What is the point? At a convention, each party formally nominates its candidates for president and vice-president, and the party unveils its party platform, or manifesto.
2. Who is going? There are about 5,000 delegates attending, selected at state and congressional district conventions, and representing each US state and territory. Plus about 15,000 journalists and tens of thousands of other party grandees, lawmakers and guests.
3. What is the schedule?
- Monday speakers – First Lady Michelle Obama, Massachusetts Senator Elizabeth Warren, Vermont Senator Bernie Sanders,
- Tuesday – Former President Bill Clinton, Trayvon Martin’s mother Sybrina Fulton
- Wednesday – President Barack Obama, Vice-President Joe Biden, vice-presidential running mate Tim Kaine
- Thursday – Hillary Clinton, introduced by daughter Chelsea