Democrat Kamala Harris has raised $540 million in little more than a month since she began her race for U.S. president, with a surge of donations flowing in during the Democratic National Convention last week, her campaign said on Sunday.

A memo released by Harris' campaign manager, Jen O'Malley Dillon, said the $540 million raised included $82 million that came in during convention week and is a sign of Democratic enthusiasm for her candidacy.

"This is the most ever for any presidential campaign in this time span," she said.

Vice President Harris became a candidate for president on July 21 when President Joe Biden stepped aside under pressure from fellow Democrats concerned about his cognitive ability after he stumbled during a June 27 debate against Republican Donald Trump.

The Harris candidacy has generated momentum that has put Trump on the defensive and he has struggled to maintain the media spotlight on him.

Harris and her vice presidential running mate, Tim Walz, take their campaign for the White House on a bus tour through Georgia this week, looking to build support in a state looming large in the Nov. 5 election.