White House nominee Joe Biden was on the verge Tuesday of revealing his running mate in the November presidential election, as Michelle and Barack Obama were confirmed as headliners of next week's Democratic National Convention.

Organisers announced that Obama will deliver a prime time speech next Wednesday, the convention's penultimate evening, while former first lady Michelle Obama will address the convention on Monday, opening night.

The schedule details were released as Biden was finalizing his choice of running mate following weeks of intense speculation about the identity of the pick.

The 77-year-old Democratic veteran is expected to reveal his vice presidential choice this week, and he has pledged to pick a woman.

Biden's campaign would not be drawn on who his running mate will be or when the announcement drops, but NBC News reported that Biden has made his choice and could announce it as early as Tuesday.

Biden has vetted multiple prospects. They include Senator Kamala Harris and Obama-era national security advisor Susan Rice, who are both black; Asian-American US Senator Tammy Duckworth; New Mexico Governor Michelle Lujan Grisham, who is Latina; and caucasian candidates including Michigan Governor Meghan Whitmer.

The Democratic nominee is leading President Donald Trump in the polls but he hopes his running mate announcement will energize his campaign -- and the Democratic base -- in the less than three months before the November 3 vote.

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

 "Joe Biden will speak about his vision for uniting America to move us forward out of constant chaos and crisis, and for delivering on that promise for all," the party said in a statement.

The unnamed vice presidential nominee is scheduled to address the convention August 19, before Obama's keynote speech.

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 driven by video presentations and appearances.

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 launch pad for Biden's final sprint to the election.

 Democrats have revealed what they hope will be an inspiring lineup of speakers, including standard bearers of the progressive left like 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 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 Harris.

On Tuesday the campaign said that 13 of Biden's former nomination rivals will make "a show of unity" at the convention by appearing via video to discuss the party's vision.

Harris is widely considered a top potential running mate pick, and her slot on the convention schedule -- apparently the last speaker before the Bidens on the final night -- has fueled speculation about whether the 55-year-old Californian has earned the VP nod.

Three other women seen as potential picks -- Whitmer, Warren and Duckworth -- are also on the schedule, although Rice is not.

One person who is scheduled to address the Democratic event is Ohio's Republican former governor John Kasich, who has remained a steadfast opponent to Trump.

The president had been adamant about delivering his own nomination acceptance speech at a crowded August 24-27 event in Jacksonville, Florida but he, too, has acknowledged he will have to deliver his remarks remotely.