Joe Biden dreamed of one day becoming president nearly all his life. By the time he did, he was the oldest ever to hold the office. The Biden presidency became that of a man racing the clock of his own mortal frailty. Here’s what to know about Biden’s journey to and through the presidency — and his attempts to lay the groundwork for Kamala Harris:

Biden was wary of the offer to be Barack Obama’s running mate. He accepted it only after making clear that he wanted the same deal that Walter Mondale told Biden he had gotten from Jimmy Carter: not a narrow portfolio but rather an imprint on all major issues, and being the last person the president would talk to about a policy decision before making it.

Biden’s decades of experience in the Senate were an asset to the new president, who leaned on him as a legislative sausage-maker. “He was willing to do something Obama wasn’t always eager to do — which was go to the Hill, work the members, have the dinners,” said the former deputy chief of staff Jim Messina. Biden became a trusted confidant who, according to one White House adviser, frequently urged the more deliberative Obama to “go with your gut.”

With the start of Obama’s second term in 2013 — earlier than has been previously reported — Biden and his advisers began plotting his own presidential run, according to one of them. Their efforts continued even after his son Beau died of brain cancer in May 2015.

But throughout that period, Obama discouraged the vice president’s candidacy — out of concern for his grieving friend, according to two Obama aides. Biden suspected other motives and later wrote that Obama was “putting a finger on the scale” for Hillary Clinton. Biden would recall in 2023, exposing a lasting wound, that “a lot of people” encouraged him to run for the 2016 Democratic nomination — “except the president.”

According to those close to him, Biden believed he had become president because of his instincts, honed in the Senate, to build a winning coalition — in this case, with the progressive wing of his party that felt disrespected by the Hillary Clinton campaign four years earlier. “When he became president, he felt compelled to govern with them being a part of it,” said Senator Chris Murphy, a Democrat from Connecticut, who added: “I also think Biden went through this metamorphosis.”

“For an older white man who most people would call a moderate,” said Pramila Jayapal, the chairwoman of the Congressional Progressive Caucus, “I certainly didn’t think he was going to be a progressive.”

But Biden came to see Bernie Sanders, his chief opponent in the 2020 Democratic primaries, as the standard-bearer of a movement that would be necessary for his own success as a president. When Sanders visited the White House in early 2021, he told Biden he wanted to see the bill that would become the Inflation Reduction Act funded to the tune of $5 trillion to $6 trillion. “Bernie,” the president replied, “I want to go as big as we can possibly get.”