In the opening hours of the convention, party officials struggled to carry out business as angry Sanders supporters roared their disapproval, drawing a deafening response from Clinton delegates.
"We're all Democrats and we need to act like it," U.S. Representative Marcia Fudge of Ohio, the convention's chairwoman, shouted over the uproar.
Sanders tried to head off the disruptions, sending an email to delegates as the convention opened urging them not to interrupt the proceedings.
"Our credibility as a movement will be damaged by booing, turning of backs, walking out or other similar displays. That's what the corporate media wants. That's what Donald Trump wants," Sanders said in the email.
Several speakers pleaded for peace between the Democratic factions. Comedian Sarah Silverman, a Sanders supporter, said she would support Clinton "with gusto" and admonished the Sanders fans.
"To the 'Bernie or Bust' people, you're being ridiculous," she said, drawing a roar from the crowd and another round of competing cheers between Clinton and Sanders supporters.
She and U.S. Senator Al Franken of Minnesota then introduced Paul Simon to sing his 1970 hit "Bridge Over Troubled Water."
Warren accused Trump of taking a me-first attitude and said the Republican convention had displayed his lack of ideas.
"Did you hear even one solid proposal from Trump for increasing incomes or improving your kids' education or creating even one single good-paying job?" she said.
As the convention opened, the Democratic National Committee issued "a deep and sincere apology to Senator Sanders, his supporters, and the entire Democratic Party" for the email flap and said it would take action to ensure it never happens again.
Democratic National Committee Chairwoman Debbie Wasserman Schultz resigned effective at the end of the convention over the controversy. At a morning gathering of Florida delegates, Sanders supporters booed Wasserman Schultz, whom they accuse of trying to sabotage the campaign of the democratic socialist.
The emails exacerbated the distrust of Clinton among some Sanders supporters who view her as a Washington insider paying lip service to their goals of reining in Wall Street and eradicating income inequality.
But U.S. Senator Jeff Merkley of Oregon, the only senator to endorse Sanders during the party primaries, told the convention that supporters of the two former rivals had plenty in common.
"Whether you spent this year feeling the Bern or you spent this year ready for Hillary, all of us are ready for an America that rejects discrimination and embraces diversity, that celebrates voter empowerment not voter suppression, that creates opportunity for all of us, not just the lucky few," he said.
While Sanders has endorsed Clinton, the former first lady faces a difficult task winning over his backers in the fight against Trump. The New York businessman pulled ahead in at least one opinion poll on Monday, after lagging Clinton in most national surveys for months.
A CNN/ORC opinion poll gave Trump a 48 percent to 45 percent lead over Clinton in a two-way presidential contest.
Trump was formally nominated for president at a chaotic Republican convention in Cleveland last week.
(Editing by Howard Goller)
© 2016 Thomson Reuters. All rights reserved.
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