Embattled Democratic Party chair Debbie Wasserman Schultz said she is resigning, following a leak of emails suggesting an insider attempt to hobble the campaign of Bernie Sanders in the White House primaries.

Ms Wasserman Schultz will step down at the end of the Democratic National Convention, she said in a statement on the eve of the confab in Philadelphia that is set to anoint Mrs Clinton as the party's presidential nominee.

Her departure, long sought by Mr Sanders, is aimed at drawing a line under the scandal as establishment Democrats seek desperately to unite the party behind the campaign of former secretary of state Mrs Clinton, who goes up against Republican Donald Trump in the November presidential election.

Ms Wasserman Schultz, a congresswoman from Florida said her five-year stint leading the Democratic National Committee was over.

She said she will still open and close the convention.

A cache of leaked emails from Democratic Party leaders' accounts includes at least two messages suggesting an insider effort to cripple the upstart Mr Sanders' campaign that had competed with Mrs Clinton - including by seeking to present him as an atheist to undermine him in highly religious states.

The Vermont senator repeated calls today for the resignation of Ms Wasserman Schultz, whose leadership was already under fire and whose impartiality was called into question by the leaks.

US President Barack Obama said he called Ms Wasserman Schultz today to say he was "grateful" for her years of service.

"I always said that Debbie Wasserman Schultz was overrated. The Dems convention is cracking up," Donald Trump taunted on Twitter.