Former President Barack Obama endorsed his one-time running mate and vice president Joe Biden on Tuesday, delivering a seal of approval that Obama had withheld while the race for the Democratic presidential nomination was still competitive.

“I’m so proud to endorse Joe Biden for president of the United States,” Obama said in a YouTube video. “Choosing Joe to be my vice president was one of the best decisions I ever made.”

In his endorsement video, Obama listed Biden’s responsibilities in his presidential administration — implementing the Recovery Act, managing the H1N1 and Ebola pandemics, and helping to “restore America’s standing and leadership in the world.”

Biden “has the character and experience to guide us through one of our darkest times and heal us through a long recovery,” the former president said.

Obama also addressed the current economic and health crises caused by the COVID-19 pandemic, calling for a public health insurance option and saying that Biden would surround himself with “experts, scientists and military officials who actually know how to run the government.”

Obama’s endorsement came after Biden’s last serious competitor, Sen. Bernie Sanders (I-VT), bowed out last week.

On Monday, Sanders himself endorsed Biden in a live-streamed video chat, pointing out areas of agreement between the candidates and saying, “we’ve got to make Trump a one-term president and we need you in the White House.”

Obama, in his remarks Tuesday, took a minute to address the field of Democratic contenders Biden defeated to secure the nomination, particularly Sanders. Obama called the Vermont senator “an American original” who had successfully given a voice to working people.

There are some holdouts in Biden’s recent wave of support: Sen. Elizabeth Warren (D-MA) has not formally endorsed her former competitor yet — though The New York Times reported Monday that she was expected to, and that she had left the timing of an announcement up to Biden’s campaign.

Rep. Alexandria Ocasio-Cortez (D-NY), a former top Sanders campaign surrogate, said it would take “uncomfortable” concessions from Biden to earn her enthusiastic endorsement — though she said she would support the nominee.

Sanders’ national press secretary Briahna Joy Gray, among other members of his campaign staff, announced publicly Monday that she was not endorsing Biden.

A large part of Obama’s video focused on the Trump administration and congressional Republicans, who the former President said it was essential to remove from office.

“The Republicans occupying the White House and running the U.S. Senate are not interested in progress,” Obama said. “They’re interested in power.”

The GOP, Obama said, sought to kick people off of their existing health insurance during a pandemic — a seeming reference to the ongoing legal effort by the Trump administration and Republican attorneys general against Obamacare. They’ve “denied the science of climate change just as they denied the science of pandemics.” And they’ve “disregarded” principals of rule-of-law, voting rights and transparency, he said.

In 2016, Obama similarly waited until the competition was all-but-over to endorse his former Secretary of State, Hillary Clinton, for the party’s nomination. Obama formally backed Clinton’s bid a few days after she secured an outright majority of pledged and “super” delegates — though Sanders kept campaigning for five more weeks before endorsing Clinton.

Despite mostly staying out of the Democratic primary race when there were multiple candidates in the field, some reporting indicates that Obama had a hand in coalescing support behind Biden.

Multiple outlets reported that Obama and former South Bend Mayor Pete Buttigieg spoke on the phone after Buttigieg dropped out of the race following a disappointing performance in the South Carolina primary early last month.

Obama noted Buttigieg’s considerable leverage during the call, the Times reported, but did not ask him outright to endorse Biden. Within a day, Buttigieg had endorsed Biden — and so did Sen. Amy Klobuchar (D-MN), the other remaining moderate in the field.

Crucially, the pair threw their weight behind Biden a day before “Super Tuesday,” asking supporters of theirs eager to unite the party behind a single person to support the former vice president. Biden made himself the definitive favorite for the nomination with a strong performance the next day.

The Times reported Tuesday that Obama and Sanders had spoken several times in recent weeks — and that Obama had told a friend he needed to “accelerate the endgame.”

While Sanders’ exit last week marked the end of the race, Obama’s endorsement marked the passing of the torch.

“Now is the time to fight for what we believe in,” Obama concluded. “So join us. Join Joe.