Joe Biden has insisted he doesn't want Barack Obama's endorsement in his third run for the presidency.

But if history is any gauge, Obama had no intention of going out on a limb for his former VP this time around.

The 'bromance' between the former president and Joe Biden that blossomed when Obama took office in 2008, dissipated in the post-White House years, according to an upcoming book about the pair: Barack and Joe: The Making of an Extraordinary Partnership.

While the two men did develop a strong affection for one another, there were times Biden drove Obama over the edge as the book reveals a younger Obama once rolled his eyes at Biden's constant babbling, sending a note to his adviser saying: 'Shoot. Me. Now.'

And it was a political embarrassment for Biden when Obama failed to step up and support his former vice president in both the 2016 and 2020 presidential races.

The 'bromance' between Barack Obama and Joe Biden dissipated in the post-White House years, according to an upcoming book about the pair

It was a political embarrassment for Biden when Obama failed to endorse him in the 2020 presidential race and stated in that there was a need for 'new blood' in Democratic Leadership (pictured at this months Democratic Debate)

Once brothers in arms, the president was unwilling to encourage Biden to run against Hillary for the Democratic nomination in the 2016 presidential race, a lifelong dream of Biden's. Obama was more concerned about what a Republican victory would mean for his place in history and put his health care program at risk.

The president needed to extend his legacy and he didn't believe that Joe could beat Hillary.

The details of their relationship are revealed in Barack and Joe: The Making of an Extraordinary Partnership out October 8

'Joe, despite his many virtues, was just another white guy, one in a long line of American presidents — hardly the symbol of the Teutonic change that Obama hoped would mark his place in the history books', writes Steven Levingston, author of Barack and Joe, published by Hachette Books on October 8.

'Barack had placed his bet on Hillary, the one he believed would confirm his revolutionary stamp on American's political culture - the first black president passing the baton to the first woman president'.

Obama stated in January 2019 that there was a need for 'new blood' in the Democratic leadership.

Refusing to endorse him in 2020 was yet another blow to Biden who believed there was deep love between the two men.

But 'that's different than giving his brand to him,' the book states.

To cover his hurt, Biden then insisted that he had asked Obama not to endorse any candidate during the primary season.

'Whoever wins the nomination should win it on their own merits', Biden stated after Obama declined support. But he was offended yet again when Obama met with other potential presidential candidates, including former Texas Congressman Beto O'Rourke, before Biden had even made his decision to run.

What had been an unprecedented closeness between a president and vice president had changed.

'Now they were two high profile politicians considering their own futures' — and no longer brothers in arms they once were.

In the beginning, 'from a gaffe-meister, Biden had shaped himself into a conscientious, well informed partner to the president emerging as the heart to Obama's brain', writes the author.

Biden always had his eye on the Oval Office and made a promise to his son, Beau, when he was dying of brain cancer in 2015, that he would try for a third run for the presidency despite his lousy track record.

Obama had been thinking about the presidency for two decades and experienced an epiphany in 1987 at age 25 that politics was his calling. In 2008, Obama and Biden were rivals for the biggest political trophy in the world, 'each driven by raw political ambition and his belief in his own superior fitness to sit in the Oval Office. It was not a fertile ground for friendship'.

It seemed so unlikely when Obama first came calling to ask Biden to consider a position in his presidency and he had only to choose between Vice President and Secretary of State — a surprise to Hillary Clinton who thought the latter position was only offered to her.

She wasn't offered the post of vice president because Obama and his aides believed she had too much baggage along with Bill Clinton, 'too large a presence and unpredictable'.

'If I picked her, my concern is that there would be more than two of us in the relationship', Obama told David Plouffe, his adviser.

Biden was always gaffe prone with an unruly tongue yet he was a veteran of 32 years in the Senate chamber and had chaired the Foreign Relations Committee when Obama arrived as a freshman senator in 2005.

Obama placed his bets on his former Secretary of State Hillary Clinton to win the 2016 Democratic Primary and therefore didn't endorse his vice president

It has always been a dream of Joe Biden's to be president, launching his first bid for the presidency in 1988

Despite the lack of endorsement, the men continued to have a deep love for one another, but 'that's different than giving his brand to him,' the book states

One year earlier, as a little known Illinois state senator running for a U.S. Senate seat, Obama stepped into one of the biggest national spotlights when he spoke at the Democratic National Convention in Boston in July 2004 before Senator John Kerry accepted the party's nomination for president.

In that instant on stage, Obama became a national symbol and the new face of the Democratic Party.

Fast forward a year, he was now the lowest ranking member on the Senate Foreign Relations Committee - Joe's turf - and the average age of his colleagues was 60 while he was only 43.

Barack had placed his bet on Hillary, the one he believed would confirm his revolutionary stamp on American's political culture - the first black president passing the baton to the first woman president Author Steven Levingston

Seeing Obama's momentum, Biden raised his hand like a traffic cop to advise the young Senator.

'He's a good man but tell him he needs to go slow when he gets to the Senate', Biden advised.

But Obama quickly became impatient with Biden's grandstanding and ability to drone on…and on...and on. Just listening to Biden's ad nauseam babbling, he rolled his eyes and sent a note to his adviser Robert Gibbs: 'Shoot. Me. Now'.

But the young cerebral African American who sweated over the precision of his words and an older, chummy white guy given to impulsively speaking his mind — 'initially circled each other wearily' but that evolved into admiration, respect and a feeling of true companionship.

They were both athletes and spoke using sports metaphors. They loved their wives, their kids, and they slipped quickly into a genuine camaraderie – once they were in office together.

Obama was aloof, Biden gregarious.

Obama had watched him speaking bluntly in a world of political calculation and accepted him as authentic.

His was 'a generational way of talking' but Obama learned to accept Joe as Joe and look past 'his mangled way of expressing himself'.

'I understand what Joe meant. I know what's in his heart', Obama often said.

But there were major stumbles that could have derailed any friendship.

Biden got out ahead of Obama in support of gay marriage forcing the White House to support it before they were ready.

Speaking off the cuff to reporters in DC after both were running for president in 2008, Biden stepped into deep water saying, 'I don't recall hearing a word from Barack about a plan or a tactic.

'I mean you got the first sort of mainstream African American who is articulate and bright and clean and a nice-looking guy. I mean, that's a storybook, man'.

Obama was unwilling to support Biden in the 2016 presidential race, a lifelong dream of Biden's. He's pictured in 2015 announcing he will not run for president alongside Obama and wife Jill

The men quickly slipped into a genuine camaraderie once they were in the office together, sharing a strong love for their wives and their kids

An explosive and racially insensitive remark that Obama addressed by reminding Biden that there had been previous African American presidential candidates and they were all articulate - Jesse Jackson, Shirley Chisholm, Al Sharpton.

Biden hadn't developed any affection for Obama after he soundly lost the Iowa race and declined to help Obama in the remaining primaries citing his friendship with the Clintons.

He opted to remain neutral for the rest of the campaign and only discovered a new respect for the freshman senator when Obama had to face critics opposed to his former pastor's inflammatory words condemning America as a Ku Klux Klan nation and accusing America as being responsible for the September 11 attacks with its history of racial terrorism.

Obama's advisers believed this whole brouhaha was instigated by the Clinton campaign.

Obama condemned Pastor Jeremiah Wright's words but also stated the country needed to confront the issue of race. His speech marked a new sense of fraternity that Biden found with Obama although he was still smarting from his loss to him in Iowa.

Biden had his own passion for civil rights working as a lifeguard at a public swimming pool in the summer of 1962 when he suddenly realized he was the only white person the attendees knew and they wanted to know all about his world.

Biden learned they got reminders every day they didn't belong in this country and he now joined in racial protests and was filled with racial fervor.

I love this guy and he's got heart President Barack Obama on Vice President Joe Biden

He later stated he ran for the U.S. Senate because of his passion for civil rights. He wanted to make a change.

'Some black people believed that Biden had the racial 'it' factor.

'Similar to Bill Clinton, he knew the secret handshakes of blackness and was able to joust with blacks in familiar and in humorous fashion', writes Levingston.

'In one sense, the perception was that the blackest man in the White House was the white guy'.

Obama had grown up in Hawaii and Indonesia abstracted from some elements of black life and culture.The imagery of the black man on top and white man subordinate flipped the script.

This was the most significant relationship between vice president and president in this country's history. They worked harmoniously together, respected and grew to love each other.

Typically the vice president's job was the most insignificant office and required no more than carrying out ceremonial duties or being sent to faraway places doing much of nothing.

Franklin D. Roosevelt's first vice president, John Nance Garner described the job as not 'worth a bucket of warm p*ss'.

Ike and Nixon never had a warm relationship.

When asked if there was one idea of Nixon's that he had adopted, Eisenhower responded, 'If you give me a week, I might think of one'.

Kennedy sent Johnson away on overseas missions so often Johnson felt that his presence just bugged Kennedy.

Before Biden accepted the post, he laid out a list of demands that included being Obama's chief counselor, inclusion in every important meeting, and being able to advise honestly in all legislative efforts.

Before Biden accepted the post of vice president, he laid out a list of demands that included being Obama's chief counselor, inclusion in every important meeting, and being able to advise honestly in all legislative efforts

Obama and Biden's relationship was the most significant between vice president and president in this nation's history by working harmoniously together, respecting and growing to love each other

'He wanted to be the last guy in the room whispering in Obama's ear', writes the author. Joe had grown up in Scranton, Pennsylvania, and Wilmington, Delaware, with a serious stutter and was called Bu-Bu-Biden.

He was also dubbed Dash - describing how words came out.

'I talked like Morse code', Joe said. 'You gu-gu-gu-gu-guys sh-sh-sh-sh-shut up'.

Schoolmates thought he was stupid.

He practiced quoting Irish poets while looking in the mirror to overcome his affliction.

He got hair plugs when his hair was still dark - less obvious now - to look younger.

Weighing on Obama's self-image was his chubbiness until seventh grade that made schoolmates laugh at him.

He took up jogging to get his weight down but once being the fat boy made him sensitive about his weight well into his twenties.

Obama chose Biden for his veteran senatorial experience, skill working with congress, and foreign policy expertise as well as Joe's sensitivity and ability to overcome personal setbacks.

'I love this guy and he's got heart', Obama said and granted him the expansive role he requested as vice president knowing that they would have to 'deal with him every day to make sure he stays in the corral'.

Now he may be out of touch in the #MeToo era – with his folksy charm and physical affection but he was an effective vice president for eight years and there was a huge amount of love between the two men.