PHILADELPHIA -- Debbie Wasserman Schultz said Sunday that she's resigning as chairman of the Democratic National Committee, announcing the leadership shake-up as party officials gather in Philadelphia to nominate Hillary Clinton for president.

Wasserman Schultz's announcement came after WikiLeaks released 19,000 emails from party officials, some suggesting the Democratic National Committee favored Clinton during the primary, despite pledging neutrality. The leaked emails prompted primary runner-up Bernie Sanders to call for Wasserman Schultz's immediate resignation.

"The party now needs new leadership that will open the doors of the party and welcome in working people and young people," Sanders said.

Wasserman Schultz, in a statement released Sunday, said: "I know that electing Hillary Clinton as our next president is critical for America's future. I look forward to serving as a surrogate for her campaign in Florida and across the country to ensure her victory."

Her statement did not address the email leak.

Wasserman Schultz, a member of Congress from south Florida, said her resignation will take effect upon the close of the convention. Her decision came as she received many calls to step aside, including strong pressure from the Clinton campaign, according to a senior Democrat familiar with the negotiations.

Donna Brazile, a longtime Democratic strategist, will take over as interim chairman, according to the Democratic National Committee.

Democrats are trying to avoid the tumult seen at last week's Republican National Convention, when runner-up Ted Cruz pointedly and publicly refused to endorse nominee Donald Trump. As Sanders demanded Wasserman Schultz's resignation, he made clear he wants to see Clinton in the White House.

"I'm going to do everything I can to defeat [Trump], to elect Hillary Clinton and to keep focusing, keep focusing on the real issues facing the American people," Sanders said on CNN.

Clinton and Obama both praised the departing party chief, hoping to move past the disputes and on to today's launch of a celebration featuring elected officials and celebrities who will try to re-introduce Clinton to a general election audience.

Trump took the opportunity to poke at his rivals, writing in a Twitter post Sunday that "The Dems Convention is cracking up." His campaign chief, Paul Manafort, went further and called on Clinton to drop out of the race.

At the Republican convention, Trump cast himself as the law-and-order candidate in a nation suffering under crime and hobbled by illegal immigration. As he accepted the Republican nomination, Trump said: "The legacy of Hillary Clinton is death, destruction, terrorism and weakness."

In response, Clinton seized upon what she called the "fear and the anger and the resentment" from Trump and Republicans, dismissing Trump's declaration that only he could fix the problems that afflict the nation.

"Donald Trump may think America's in decline, but he's wrong. America's best days are still ahead of us, my friends," Clinton said during a campaign event Saturday in Miami.

Democrats still divided

Sanders will address the convention tonight, and Obama will speak Wednesday night. Other high-profile speakers include first lady Michelle Obama, former President Bill Clinton and Vice President Joe Biden.

They will try to overcome party disunity that could be a factor in Philadelphia, given Wasserman Schultz's resignation and the unhappiness among many Sanders supporters that was intensified by both the email leak and by Clinton's pick of Sen. Tim Kaine of Virginia to be her running mate.

"If they think they can win without half the party, let them lose," said Andrew Fader, 27, of New York, who was wearing a "Bernie" T-shirt on Sunday near the Liberty Bell in Philadelphia. "And I'll move to Canada."

Norman Solomon, a delegate who supports Sanders, said Wasserman Schultz's removal was unlikely to soothe those who back the Vermont senator. He said there is talk among Sanders delegates of walking out during Kaine's acceptance speech or turning their backs as a show of protest. Sanders supporters say Kaine is not liberal enough.

Sanders endorsed Clinton two weeks ago after pressing for the party platform to include a $15-an-hour minimum wage, debt-free college and an expansion of access to health care.

At a meeting of the convention rules committee Saturday, liberal Sanders supporters pushed for changes to the party's nominating process. They did not succeed in passing an amendment abolishing superdelegates, but they did win a compromise with the Clinton camp -- a "unity commission" that will review the overall procedures and will seek to limit the role of superdelegates in future elections.

The 21-member commission will study a number of issues, including how to improve access to caucuses and how to broaden the party's appeal. For superdelegates, the commission's recommendation is that congressional members, governors and other elected officials should remain as unpledged delegates, but that other delegates would be bound proportionally to the results of state primaries.

Sanders campaign manager Jeff Weaver endorsed the plan, saying it would "result in the reduction of superdelegates as we know them by two-thirds." The Clinton campaign also expressed support for the commission.

Any changes to superdelegate rules would be subject to national committee approval. A report by the commission is due by Jan. 1, 2018.

Philadelphia protests

Away from the convention proceedings, thousands of demonstrators walked Philadelphia's sweltering streets on Sunday, cheering, beating drums and chanting, "Hell, no, DNC, we won't vote for Hillary."

"Debbie Wasserman Schultz and Hillary's orchestrated collusion cheated thousands of honest Americans, who have invested enormous amounts of money and personal time for real change," said one of the marchers, Dan Haggerty, 54, an electrician from California.

Darcy Samek, 54, traveled alone from Minneapolis to protest through the four-day convention. She said Wasserman Schultz has been a "miserable failure" who needed to depart.

"Everyone kind of knew [the Democratic Party was against Sanders], but that doesn't mean it will change now that it's proven," she said. "It's just more of the same."

Philadelphia Police Commissioner Richard Ross and other officers walked alongside Sanders protesters. Ross said he liked what he saw Sunday: a peaceful protest.

The heat wave that descended on the city was showing no mercy, with temperatures reaching the high 90s and the city under an "excessive heat" warning by the National Weather Service. It's expected to peak today with temperatures possibly hitting 100 degrees.

Just as in Cleveland during the Republican convention, Philadelphia police were using bicycles as barricades along the streets, and volunteers were handing out water to marchers. Shoppers walked out of stores to watch the march as if it were a parade.

Chants of "Bernie! Bernie!" were countered by chants of "Hillary! Hillary!"

On Sunday night, more than 1,000 people joined Hollywood stars including Shailene Woodley, Susan Sarandon and Danny Glover in Philadelphia for a climate rally. They vowed to keep fighting on climate and environmental issues, even though their preferred presidential candidate, Sanders, would not be driving the party's agenda.

Leak blamed on Russia

Clinton's campaign manager, Robby Mook, tried Sunday to shift blame for the email leak away from Democratic National Committee officials and onto "Russian state actors" who, he said, may have breached Democratic National Committee computers "for the purpose of helping Donald Trump."

"What's disturbing to us is that experts are telling us that Russian state hackers broke into the DNC, stole these emails, and other experts are now saying the Russians are releasing these emails for the purpose of actually helping Donald Trump," Mook said on CNN's State of the Union. "I don't think it's coincidental that these emails were released on the eve of our convention here, and that's disturbing."

How the emails were stolen hasn't been confirmed.

"It was concerning last week that Donald Trump changed the Republican platform to become what some experts would regard as pro-Russian," Mook said.

The Washington Post reported last month that Russian government hackers penetrated the Democratic National Committee, stealing opposition research about Trump and compromising the party's email and chat systems.

But that explanation seems unlikely to mollify Sanders supporters who are angry about the messages and distrustful of Clinton and the party.

Party wrangles aside, Clinton is within days of her long-held ambition to become the party's official presidential nominee.

After the Democratic National Committee released a slightly trimmed list of superdelegates -- those are the party officials who can back any candidate -- it now takes 2,382 delegates to formally clinch the nomination. Clinton has 2,814 when including superdelegates, according to an Associated Press count. Sanders has 1,893.

Information for this article was contributed by Ken Thomas, Catherine Lucey, Anne Flaherty, Julie Pace, Chad Day, Hope Yen, Alan Suderman, Alex Sanz, Megan Trimble and Geoff Mulvihill of The Associated Press and by Anne Gearan, Abby Phillip, Philip Rucker, David Weigel, Karen Tumulty and John Wagner of The Washington Post.

A Section on 07/25/2016