Democratic National Committee Chairwoman Debbie Wasserman Schultz speaks during a campaign event for Democratic presidential candidate Hillary Clinton at the Florida State Fairgrounds Entertainment Hall in Tampa, Fla., on Friday. On Sunday, Wasserman Schultz announced she would resign at the end of the week following the release of thousands of documents suggesting the DNC played favorites for Clinton during the primary election.
Democratic National Committee Chairwoman Debbie Wasserman Schultz speaks during a campaign event for Democratic presidential candidate Hillary Clinton at the Florida State Fairgrounds Entertainment Hall in Tampa, Fla., on Friday. On Sunday, Wasserman Schultz announced she would resign at the end of the week following the release of thousands of documents suggesting the DNC played favorites for Clinton during the primary election. Credit: AP

On the heels of a tumultuous Republican convention, Hillary Clinton hopes her gathering in Philadelphia will show off a forward-looking Democratic Party united behind her steady leadership. But to do that, she must overcome lingering bitterness among supporters of defeated rival Bernie Sanders and a political mess and last-minute leadership shake-up of the partyโ€™s own making.

The Democratic National Convention was set to kick off today as a week of optimistic celebration with high-powered elected officials and celebrities re-introducing Clinton to a general election audience. But the effort was complicated by the publication of 19,000 hacked emails on the website Wikileaks, suggesting the Democratic National Committee had played favorites for Clinton during the primary.

The chairwoman of the Democratic National Committee, Debbie Wasserman Schultz, announced abruptly Sunday afternoon that she would step down at weekโ€™s end. Sanders had called earlier Sunday for her departure.

Wasserman Schultz has been a lightning rod throughout the presidential campaign for criticism from the partyโ€™s more liberal wing, with Sanders repeatedly accusing the national party of favoring Clinton despite officially being neutral.

โ€œIโ€™m not shocked, but Iโ€™m disappointed,โ€ Sanders said of the hacked emails, one of which questioned whether his religious beliefs could be used against him, on ABCโ€™s This Week.

Clinton and President Obama each released statements praising Wasserman Schultzโ€™s leadership. โ€œThereโ€™s simply no one better at taking the fight to the Republicans than Debbie,โ€ Clinton said.

The self-inflicted wounds could hamper the Clinton campaignโ€™s effort to portray the partyโ€™s convention in a different light from the just-concluded Republican gathering in Cleveland. Donald Trump accepted the GOP nomination, but party divisions flared when his chief rival, Texas Sen. Ted Cruz, refused to endorse the billionaire businessman.

Trump appeared to relish in the Democratic chaos Sunday, writing, โ€œThe Dems Convention is cracking up.โ€

At the Republican convention, Trump cast himself as the law-and-order candidate in a nation suffering under crime and hobbled by immigration, sticking to the gloom-and-doom theme. As he accepted the Republican nomination, Trump said: โ€œThe legacy of Hillary Clinton is death, destruction, terrorism and weakness.โ€

In return, Clinton seized upon what she called the โ€œfear and the anger and the resentmentโ€ from Trump and Republicans, dismissing Trumpโ€™s declaration that only he could fix the problems that afflict the nation.

โ€œDonald Trump may think Americaโ€™s in decline, but heโ€™s wrong. Americaโ€™s best days are still ahead of us, my friends,โ€ Clinton said during a campaign event Saturday in Miami.

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

But party disunity is certain to also be a factor in Philadelphia, given Wasserman Schultzโ€™s departure and the general unhappiness among many Sanders supporters, intensified by both the emails and by Clintonโ€™s pick of Sen. Tim Kaine of Virginia to be her running mate.

Norman Solomon, a delegate who supports Sanders, said there is talk among Sandersโ€™s delegates of walking out during Kaineโ€™s acceptance speech or turning their backs as a show of protest. Sandersโ€™s supporters believe 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.

Liberal Sanders supporters pushed for changes to the party nominating process at a meeting of the party rules committee Saturday. They did not succeed in an effort to pass an amendment abolishing superdelegates, but they did win a compromise deal with the Clinton camp โ€“ a โ€œunity commissionโ€ that will review the overall procedures and will seek to limit the role of superdelegates in future elections.

On the hacked emails, Clintonโ€™s campaign manager, Robby Mook, tried to shift blame away from DNC officials to โ€œRussian state actorsโ€ who, he said, may have hacked into DNC computers โ€œfor the purpose of helping Donald Trump,โ€ the Republican presidential nominee.

How the emails were stolen hasnโ€™t been confirmed.

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

Party wrangles aside, Clinton is within just days of her long-held ambition to become the partyโ€™s official presidential nominee.

After the DNC released a slightly trimmed list of superdelegates โ€“ those are the party officials who can back any candidate โ€“ 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.