Joe Biden, the presumptive Democratic nominee for United States president, said in a new interview that he would pick former First Lady Michelle Obama as his vice presidential candidate "in a heartbeat" if he thought she would take the job.

In an interview with KDKA television station in Pittsburgh, Pennsylvania, however, Biden said he doubted she would accept the offer.

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"I'd take her in a heartbeat," Biden said. "She's brilliant. She knows the way around. She is a really fine woman. The Obamas are great friends."

But "I don't think she has any desire to live near the White House again," Biden added.

It is not the first time the former vice president, who served two terms under President Barack Obama and is on reportedly good terms with his former boss, has said he would love to have Michelle Obama alongside him in the White House. At a campaign stop in Iowa in January, he said as much and added that he also would like to put Barack Obama on the US Supreme Court.

In Monday's interview, Biden said his search for a running mate was continuing and reiterated his pledge to select a woman, but declined to commit to selecting a woman of colour in the role.

"In terms of who to pick, we're just beginning the process," he said. "We'll shortly name the committee to review this and begin to look through the backgrounds of the various potential nominees. And that's just getting underway."

The Democrat's vetting process for a running mate has been playing out in an unusually public manner in recent days, with potential contenders for the job making appearances on a podcast Biden launched earlier this month that is recorded in his Delaware home.

While many Democrats have openly fantasised about the prospect of Michelle Obama being Biden's running mate, the former first lady has made it abundantly clear that she has no interest in the role and said she would stick to her "get-out-the-vote" efforts instead.

"I’ll say it here directly: I have no intention of running for office, ever," she wrote in her best-selling memoir, "Becoming," released in 2018.

We can still make a difference even as we #StayHome. Excited to join @whenweallvote's #CouchParty tonight with my friends @tomhanks and @RitaWilson!



And of course @djdnice will be playing a live set while we spread the word! Join us at 7:15pm ET: https://t.co/JNUGoT7xUw pic.twitter.com/KEfwA3aRd8 — Michelle Obama (@MichelleObama) April 20, 2020

Among those in contention are former campaign trail rivals Amy Klobuchar, a Senator from Minnesota, Massachusetts Senator Elizabeth Warren, and California Senator Kamala Harris. Also said to be in contention are Michigan Governor Gretchen Whitmer and Stacey Abrams from Georgia.

Neither Biden nor incumbent President Donald Trump have been able to campaign in public since the start of the coronavirus pandemic and the ensuing stay-at-home orders across the country.