On Thursday, two of America's queens of talk, Oprah and Ellen, released footage from interviews with Vice President Joe Biden, which will air in full later this week.

'I have a regret that I am not president,' Biden candidly told Oprah, for an interview with OWN, which airs Sunday. 'Because I think there's so much opportunity. I think America's so incredibly well-positioned.'

On Ellen, the comedian pleaded with the ex-vice president to run for the presidency in 2020.

'Just remember, that is what I'd like to see,' Ellen said. 'I don't know if it's going to be myself or Oprah as your running mate,' she said, grabbing his hand.

Vice President Joe Biden sat down with Oprah for an interview that is airing on Sunday and talked about why he didn't run for president in 2016

He told Oprah (pictured) that while he thought he was the best candidate for the job, he couldn't give the run everything after the death of his eldest son, Beau, who was also in politics

Former Vice President Joe Biden (left) sat down with Oprah (right) as part of his book tour for his forthcoming tome, 'Promise Me, Dad'

For her part, Ellen (right) begged former Vice President Joe Biden (left) to jump into the next presidential race in 2020 - saying either she or Oprah would be his running mate

After the ask, former Vice President Joe Biden (left) and Ellen (right) grabbed hands. The ex-veep has said he's decided not to decide yet, leaving the door open for a run

Biden told Ellen that right now he just wanted to focus on 'my boy,' the late Beau Biden.

The title of the ex-veep's new book, 'Promise Me, Dad,' comes from Beau asking that the former vice president be OK as his son faced the cancer that eventually killed him.

It was that grief over losing Beau, Biden said, that kept him from entering the presidential race, which the Democrats eventually lost to now President Donald Trump.

'Oprah, no woman or man should announce they are running for president unless they can answer two questions: One, do they truly believe they are the most qualified person for that moment. I believed I was,' Biden said.

It was the second question that stopped him.

'But was I prepared to be able to give my whole heart, my whole soul and all my attention to the endeavor?' he mused. 'And I knew I wasn't.'

In another clip from the interview, he repeats that he knew, a month out, that Hillary Clinton's candidacy was doomed.

'A month out, I came back and said, we're going to lose this election,' Biden said.

In June, Politico reported that Biden had said at a donor conference that he knew a month out that Clinton would lose key battleground states.

Biden, however, had not previously expressed that publicly.

He also campaigned furiously for Clinton in those waning weeks.

OBAMA'S CHOICE: If Vice President Joe Biden (left) had entered the presidential race in 2016 President Obama would have been forced to choose between his veep and his former Secretary of State Hillary Clinton (right)

In a DailyMail.com exclusive peek at Biden's new book, he wrote that he believed he could win the election.

And he was especially potent in Clinton's electoral trouble spots.

'My numbers on trustworthiness, honesty, and empathy were as high as they had ever been,' he wrote, looking back to the time where he was mulling a campaign. 'And I was strongest where the most formidable candidate, Hillary Clinton, was weakest: the key swing states like Pennsylvania, Ohio and Florida.'

Biden revealed that he was also guided by President Obama not to run.

'In January 2015 the president was convinced I could not beat Hillary, and he worried that a long primary fight would split the party and leave the Democratic nominee vulnerable in the general election,' Biden wrote.

Biden said Obama had become 'preoccupied' with the predicament of whether Biden would run, which would pit his vice president against his former secretary of state.

Obama, Biden acknowledged, was 'subtly weighing in against' it.

'Barack and I knew, coverage in the West Wing would shift from his agenda to my chances. I also believe he had concluded that Hillary Clinton was almost certain to be the nominee,' he said.

Biden also feared the wrath of Clinton's supporters who he feared would 'stop at nothing' to quash a potential Biden bid.

In trying to help his wife, former President Bill Clinton distanced himself from a 1994 crime bill he signed into law.

'He was now calling it a big mistake,' Biden noted.

A negative news story had come out tying Biden to the unpopular legislation, articulating his role in its passage as chairman of the Senate Judiciary Committee.

'And Clinton backers sent a signal that they would not stop at voting records and policies if I did get in the race,' Biden said.

Things got worse in October 2015 when Politico published a piece, 'EXCLUSIVE: Biden himself leaked word of his son's dying wish,' as Beau Biden had reportedly pushed his father to run for president.

'The vice president is in mourning. He's also calculating,' the piece charged.

In the book, Biden wrote, 'I should have seen this coming, I guess.'

'The Politico story exceeded even my worst expectations of what the opposition was going to be like,' he wrote. 'The idea that I would use my son's death to political advantage was sickening.'

Later that month, Biden appeared in the White House Rose Garden and said he wouldn't be a candidate.

In the months following, Biden family drama created headlines too, including son Hunter's bitter divorce from his wife Kathleen, who accused him of doing drugs and hiring prostitutes, blowing the family's money on these hobbies.

Then Hunter Biden would start a relationship with his dead brother's wife, Hallie.

But Joe Biden won't close the door on running for office again.

'I've decided I'm not going to decide not to run,' he recently told Vanity Fair.