The head of the Democratic Party resigned on Sunday amid a furore over leaked emails, hoping to head off a growing rebellion by Bernie Sanders' supporters on the eve of the convention to nominate Hillary Clinton for the White House.
The Democratic National Convention (DNC) will open on Monday 2000 GMT, amid speeches from a top line-up including Michelle Obama and Sanders. Sanders lost the primary race but he has endorsed his bitter rival, and in a show of unity he has been offered a prime speaking slot on day one of the four-day confab.
However, lingering bitterness from the heated primary campaign between Clinton and Sanders erupted after nearly 20,000 DNC emails leaked on Friday confirmed Sanders' frequent charge that the party played favourites in the race.
In a statement, DNC Chairperson Debbie Wasserman Schultz said the best way for the party to accomplish its goal of putting Clinton in the White House was for her to step aside after the convention. Sanders had demanded earlier in the day that Wasserman Schultz resign.
Wasserman Schultz said she would still open and close the convention, but the move carries risks, especially if she is booed when she takes the stage.
After a hard-fought primary campaign, the party had been heading to the convention seeming far more unified than the Republicans, whose fissures were laid bare last week as they confirmed Trump as their flagbearer at a raucous convention in Cleveland.
The email scandal also overshadowed preparations in Philadelphia for Clinton's coronation as the nominee to face Trump in the November 8 presidential election. She will be the first woman nominated for president by a major US political party.
The cache of emails leaked on Friday by WikiLeaks disclosed that DNC officials explored ways to undermine Sanders' presidential campaign, including raising questions about Sanders' faith and heritage. Sanders, who is Jewish, was tried to be described by some as an atheist during the heated-primary process.
Sanders said Wasserman Schultz, a US representative from Florida, had made the right decision for the future of the Democratic Party.
"The party leadership must also always remain impartial in the presidential nominating process, something which did not occur in the 2016 race," he said.
Despite the swirling political chaos, Sanders also made clear he would not make an insurgent bid for the nomination. "We've got to elect secretary Clinton," he told NBC's "Meet the Press."
The Clinton camp questioned whether Russians may have had a hand in the hack attack on the party's emails and were interested in helping Trump, who has exchanged words of praise with Russian President Vladimir Putin.
"What's disturbing to us is that experts are telling us that Russian state actors broke into the DNC, stole these emails and other experts are now saying Russians are releasing these emails for the purpose of helping Donald Trump," Clinton campaign chairman Robby Mook said on CNN's "State of the Union".
Trump campaign manager Paul Manafort said the Clinton camp was trying to distract from its own party's discord ahead of the convention.
"What's in those emails show that it was a clearly rigged system, that Bernie Sanders ... never had a chance," Manafort said on ABC.
"The Democrats are in a total meltdown," Trump also taunted on Twitter.
He has long sought to scoop up disaffected voters who feel Sanders was denied a fair shot at the nomination.
Clinton, 68, a former secretary of state, and Sanders, 74, an independent US senator from Vermont who ran for president as a Democrat, waged a bruising months-long battle for the nomination. Sanders galvanized young and liberal voters with his calls to rein in Wall Street and eradicate income inequality.
Sanders repeatedly voiced frustration with a DNC and party establishment he felt was stacked against him and after the email leak the resentment from Sanders and his supporters threatened to disrupt the convention.
"I'm not shocked but I'm disappointed," Sanders said of the emails earlier on Sunday on ABC's "This Week."
The emails showed DNC officials pondering various ways to undercut Sanders.
Brad Marshall, the DNC's chief financial officer, apologised on Facebook on Saturday for an email in which he discussed how some voters in upcoming nominating contests in Kentucky and West Virginia would reject an atheist.
"He had skated on saying he has a Jewish heritage," Marshall wrote in a May 5 email to three top DNC officials. No names were mentioned, but Sanders was the only Jewish candidate.
"I think I read he is an atheist. This could make several points difference with my peeps. My Southern Baptist peeps would draw a big difference between a Jew and an atheist."
Clinton told CBS's "60 Minutes" in an interview that aired on Sunday that she had not read any of the emails but it was "wrong and unacceptable" to bring religion into the political process.
The emails angered many Sanders supporters who were already dismayed by Clinton's choice on Friday of low-key Virginia US Senator Tim Kaine as her vice presidential running mate. Kaine, 58, who could appeal to independents and moderates, has never been aligned with party liberals.
Sanders, who has endorsed Clinton and will speak on her behalf to the convention on Monday, said he would have preferred she pick US Senator Elizabeth Warren of Massachusetts, a favourite of the party's liberal wing, as her number two.
"I have known Tim Kaine for a number of years [...] Tim is a very, very smart guy. He is a very nice guy," Sanders said on NBC's "Meet the Press".
"He is more conservative than I am. Would I have preferred to see somebody like an Elizabeth Warren selected by Secretary Clinton? Yes, I would have," he said.
Carrying pitchforks meant to portray Clinton as the devil, hundreds of Sanders supporters took to the streets of Philadelphia earlier on Sunday to say they felt betrayed by the DNC.
"It just validated everything we thought, everything we believed to be true, that this was completely rigged right from the beginning, and that you know it was really about what they were doing to set it up so she would win," Sanders supporter Gwen Sperling said.
DNC Vice Chairperson Donna Brazile will serve as interim chair through the election, the DNC said on Twitter.
In an ominous sign for the party, Brazile said the drama was not yet over indicating more emails are expected to be released in coming days.
"I don't know the substance but I do know there are lots of stuff that we might have to apologise for and that's why I say you got to own it, take full responsibility and work with the staff to create a different culture at the DNC," she told CNN.
Brazile said there are likely "many thousands" of leaked emails still to come.
Donna Brazile apologizes to Sanders camp: "the e-mails, the insensitivity, the stupidity needs to be addressed.https://t.co/A1VKIikAJr
— John Nichols (@NicholsUprising) July 25, 2016
In some good news for Clinton, former New York City mayor Michael Bloomberg plans to endorse Hillary Clinton in a prime time address at the Democratic convention, the New York Times reported on Sunday.
Citing Bloomberg's adviser Howard Wolfson, the newspaper said he plans to make the case for Clinton from the "perspective of a business leader and an independent."
Former president Bill Clinton is the DNC star Tuesday, while President Barack Obama and Vice President Joe Biden take the stage on Wednesday.
Meanwhile, thousands of pro-Sanders protesters have gathered in Philadelphia, with the largest demonstration expected on Monday.