It took a debate disaster and a pressure campaign led by Pelosi. But at the DNC, Biden finally kept his promise to be a bridge to the Democratic Party's future.

• President Biden on the first night of the DNC gave a speech that just weeks ago seemed improbable.
• In cementing his legacy, the retiring Biden gave Democrats a rousing speech at the convention.
• Biden's full-throated support for Harris is poised to set off the party's generational shift.

As President Joe Biden took to the stage at the Democratic National Convention on Monday, the schedule for the first night of festivities was not the way he originally envisioned it just weeks ago.

Biden was set to partake in the revelry, with his acceptance speech planned for the last day of the convention. During that televised prime-time address in front of millions of people, he would then give a forceful defense of his presidency while asking voters to send him back to the White House for a second term.

But during his address Monday night, after stepping aside as the Democratic nominee in late July, Biden not only outlined the policy successes of his administration but gave a full-throated endorsement of Vice President Kamala Harris, his No. 2 and the candidate who he is now counting on to carry on some semblance of his legacy should she win the White House.

After being introduced by his daughter, Ashley, a seemingly tearful Biden greeted her and was given a stirring reception by Democrats, with so many chanting: "We love Joe."

And he had a simple message for the party faithful.

"Our best days are not behind us, they're before us," he said. "And democracy must be preserved."

How might Biden's convention address be viewed when reflecting back on his presidency?

Biden finally became the bridge to the future

During the 2020 Democratic primaries, Biden while on the campaign trail said he saw himself as a "bridge" to an upcoming cadre of next-generation leaders within the party.

Biden's selection of Harris as his vice-presidential running mate was a major step in cementing the then-55-year-old California US senator as a future Democratic standard bearer.

But Biden's widely panned June debate performance against former President Donald Trump and the already-lingering voter concerns over the 81-year-old president's acuity pushed a slew of Democratic lawmakers to call on him to leave the race. And despite Biden's early resistance, he reversed course and ended his reelection bid — while also making sure he endorsed Harris as his successor.

Biden had glowing words for Harris on Monday night, telling voters that selecting her as his No. 2 was "the best decision" he's made in his career.

The president's praise for Harris' candidacy was a huge part of his address. And it came after Democratic tumult over his candidacy threatened to weaken the party as they once again face the prospect of another Trump presidency.

But on Monday (and stretching into early Tuesday in Eastern time), Biden sought to tie Harris to everything from strengthening unions to boosting investments in public safety. He also spoke of his desire to "end" the conflict in Gaza by instituting a cease-fire, and gave a nod to protestors who have relentlessly pressured Democratic leaders on the issue.

Biden projected unity during his speech, an act that'll surely further endear him to Democrats — who overwhelmingly view him favorably on a personal level — but still felt that another candidate would be a better messenger for the moment.

Harris is now that candidate, and Biden is going all in to support her campaign.

A longtime vision, upended

Before entering the Oval Office, Biden had long aspired to the presidency.

In 1973, he assumed his seat as a US senator from Delaware, and held the role until he became vice president under Barack Obama in 2009.

During that time, Biden ran for president in 1988 and 2008, faltering in each contest but never giving up on the idea. He wanted to run in 2016, but said he was discouraged from doing so by Obama, who was keen on former Secretary of State Hillary Clinton's candidacy.

Biden in 2020 won the Democratic presidential nomination and later that year unseated Trump. As he signed into law major pieces of legislation like the Infrastructure Investment and Jobs Act and the Inflation Reduction Act, he envisioned his presidency as a transformational one that could do even more in a second term.

Voter concerns over the economy and immigration played a major role in the erosion of his poll numbers over the past two years, which also threatened down-ballot Democratic candidates. And the debate with Trump eventually paved the way for Harris' ascension.

Biden is set to leave Chicago after his speech and forgo the additional days at a convention that had long been planned around his candidacy.

The president's goal of a second term is now a thing of the past. But his speech showed that he's not going to let anyone else define his legacy, no matter what the future may hold.