President Biden explains why he exited 2024 race

President Biden, who has long said he ran for the White House in 2020 due to his alarm about former President Donald Trump, decided to exit the 2024 presidential race last month . He says his decision, in part, was driven by his belief that he needed to keep the nation's focus on Trump and unite the Democratic Party ahead of the November election.

In an interview with "CBS News Sunday Morning," airing on Sunday, Aug. 11, Mr. Biden told CBS News chief election and campaign correspondent Robert Costa more about his historic decision not to seek reelection, echoing his previous statement that he would serve as a transitional figure in American presidential politics.

"When I ran the first time, I thought of myself as being a transition president," Mr. Biden, 81, told Costa. "I can't even say how old I am – it's hard for me to get it out of my mouth."

Biden expressed support for Vice President Kamala Harris, who is set to be nominated as the Democrats' standard-bearer at the party's national convention in Chicago this month.

"We must, we must, we must defeat Trump," Biden said in the interview, which took place in the Treaty Room in the White House residence.

"Although it's a great honor to be a president, I think I have an obligation to the country to do what I-- most important thing you can do. And that is — we must, we must, we must defeat Trump," he said.

Mr. Biden announced he was exiting the 2024 race and endorsed Harris as the Democratic Party's nominee on Sunday, July 21 — nearly a month after his debate against Trump, which concerned some of his Democratic colleagues and prompted dozens to call for him to withdraw .

In an Oval Office address on July 24, Mr. Biden said "nothing, nothing, can come in the way of saving our democracy," including his ambition for a second term.

A CBS News poll released on Aug. 4 showed Harris gaining momentum with a 1-point edge nationally and a tie across the battleground states. Mr. Biden was down by 5 points when he left the race.

Harris is hoping Tim Walz, the upbeat two-term governor of Minnesota, will give her Democratic ticket another boost and help her win over pivotal battleground states.