Former US president Barack Obama and his wife Michelle will deliver keynote speeches during next week's Democratic National Convention when Joe Biden will be confirmed as the party's White House challenger in the November election.

The Democratic Party announced Tuesday that Obama will give a primetime address next Wednesday, the convention's penultimate evening, while former first lady Michelle Obama will address the convention on Monday, opening night.

Biden, 77, served for eight years as Obama's vice president and will formally accept the Democratic nomination on the four-day convention's final day, August 20.

Obama, who remains one of America's most popular politicians, has campaigned virtually with Biden in recent months and has helped him raise millions of dollars in campaign cash.

The convention had been set for Milwaukee, in the battleground state of Wisconsin. But the coronavirus pandemic has upended the plans of both parties, forcing them to convert the normally raucous in-person events into online affairs.

The sudden shakeup has caused logistical challenges for both campaigns, but especially for Democrats who were hoping to use a boisterous, crowded live event as a launchpad for Biden's final sprint to the election on November 3.

Democrats have revealed what they hope will be an inspiring lineup of speakers, including standard-bearers of the progressive left like first-term congresswoman Alexandria Ocasio-Cortez.

Senator Bernie Sanders, a two-time presidential hopeful whose liberal policies like universal health care and free college have pushed Biden leftward, has been given a Monday speaking slot, along with New York Governor Andrew Cuomo.

The speaker's list includes many everyday Americans like emergency responders, teachers and factory workers.

But it is also a who's who of the party's elite, including several senators who challenged Biden for the nomination: Elizabeth Warren, Amy Klobuchar, Cory Booker and Kamala Harris.

Harris is widely considered a top potential running vice presidential pick for Biden, who is expected to announce his choice this week.

Also scheduled to address the Democrats is Ohio's former governor John Kasich, a Republican who has remained a steadfast opponent to Trump and will endorse Biden.

President Donald Trump had been adamant about delivering his own nomination acceptance speech at a crowded event in Jacksonville, Florida but he too has acknowledged he will have to deliver his remarks remotely.