Obama opened a video message with an uplifting sentiment about the fight against coronavirus and gave a thank you to those on the frontlines. He then transitioned to the political side ... saying, "That's why I'm so proud to endorse Joe Biden as President of the United States."

Obama then goes in on Trump and Republicans, saying, "One thing everybody has learned by now, the Republicans running the White House and the U.S. Senate are not interested in progress, they're interested in power."

At one point he mentions the failure of the Trump administration in containing the coronavirus, saying Republicans ignored the science of pandemics just as they ignored the science of climate change ... reminding everyone of the importance of honesty and informativeness from a President.

Biden was obviously thrilled with the endorsement, tweeting just a few minutes later, "Barack — This endorsement means the world to Jill and me. We’re going to build on the progress we made together, and there’s no one I’d rather have standing by my side."

Obama's backing of Biden comes just a day after Bernie Sanders joined Joe on a livestream to offer his endorsement, as well. Sanders dropped out of the race last week, seemingly leaving the nomination to Biden.

Joe told Bernie if he does indeed become the nominee, he's going to need Sanders' help "not just to win the campaign, but to govern."

Biden will certainly need more of Obama's help to defeat Trump, as well. The good news is ... 44 has been getting back out there more lately, mostly on social media to post helpful info about the coronavirus pandemic.

Ya gotta think he'll pivot to pushing his party to vote for Joe now though ... especially since it's been his goal to unite Democrats after all the primary chaos cooled down.