Washington — Former President Barack Obama delivered his long-awaited endorsement of Joe Biden for president on Tuesday, recording an 12-minute video to throw his support behind his former vice president.

Mr. Obama's endorsement of his former vice president comes a day after Senator Bernie Sanders gave a full-throated endorsement of Biden's presidential bid, ending speculation that the two rivals might remain at odds going into the general election season.

"I'm so proud to endorse Joe Biden to be president of the United States," Mr. Obama said. "Choosing Joe to be my vice president was one of the best decisions I ever made, and he became a good friend. And I believe Joe has all the qualities we need in a president right now."

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Mr. Obama praised Biden's actions during his administration, such as assisting in the financial recovery after the Great Recession and spearheading the response to the H1N1 pandemic. He also called for Biden's platform to go further to the left on certain issues, such as providing a public health insurance option for all Americans and expanding green initiatives to combat climate change.

Mr. Obama also hailed the field of former candidates for the nomination, especially Sanders, whom he called "an American original." He urged fervent Sanders supporters to coalesce behind Biden.

"We both know that nothing is more powerful than millions of voices calling for change. And the ideas he's championed, the energy and enthusiasm he inspired, especially in young people, will be critical in moving America in a direction of progress and hope," Mr. Obama said, referring to the Vermont senator.

The former president also spoke to Democratic voters wary of Biden by highlighting disagreements with President Trump and the Republican Party.

"Of course, Democrats may not always agree on every detail of the best way to bring about each and every one of these changes. But we do agree that they're needed. And that only happens if we win this election," Mr. Obama said. "Because one thing everybody has learned by now is that the Republicans occupying the White House and running the U.S. Senate are not interested in progress. They're interested in power."

Mr. Obama implicitly criticized Mr. Trump's response to the coronavirus outbreak, saying "pandemics have a way of cutting through a lot of noise and spin to remind us of what is real, and what is important."

"This crisis has reminded us that government matters. It's reminded us that good government matters. That facts and science matter. That the rule of law matters. That having leaders who are informed, and honest, and seek to bring people together rather than drive them apart - those kind of leaders matter," Mr. Obama said.

Mr. Obama's backing has been long expected and inevitable, but the former president has resisted engaging publicly in the presidential contest, preferring to allow 2020 candidates to make their case.

Since the first day of his campaign last April, Biden has maintained he asked Mr. Obama not to endorse him, saying he wanted to "earn this on my own."

Biden has said he has been consulting with Mr. Obama since March about the process for picking his running mate.

While Mr. Obama was not on the campaign trail, some of the loudest cheers at Biden's rallies throughout the primary process came when he mentioned his former boss. Biden proudly defended Mr. Obama's legacy from some of his rivals for the Democratic nomination, who criticized the pair for their record on issues like immigration and health care while in the White House.