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President Barack Obama formally endorsed Hillary Clinton in a video released Thursday afternoon.

"I know how hard this job can be. That's why I know Hillary will be so good at it. In fact, I don't think there's ever been someone so qualified to hold this office," he says in the video, which was tweeted by Clinton's official Twitter account.

President Obama endorses Hillary: "I don’t think there’s ever been someone so qualified to hold this office." https://t.co/KetvKoa853 — Hillary Clinton (@HillaryClinton) June 9, 2016

"I have seen her judgment, I have seen her toughness, I have seen her commitment to our values up close," he said of his former Democratic rival and first secretary of state.

Obama and Clinton will appear together in their first joint campaign trip together next Wednesday in Green Bay, Wisconsin, Clinton’s campaign said.

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The endorsement came just hours after Obama held a meeting at the White House with Clinton rival Bernie Sanders, who told reporters after the summit that he will remain in the race through the District of Columbia primary next week but indicated that he will meet with Clinton soon “to see how we can work together to defeat Donald Trump and to create a government which represents all of us and not just the one percent.”

A senior White House aide tells NBC News that the White House planned to roll out the video on Thursday "assuming the meeting went well." It was taped on Tuesday.

Clinton welcomed Obama's endorsement in an interview with Bloomberg Politics, saying "it just means so much to have a strong, substantive endorsement from the president. Obviously I value his opinion a great deal personally."

"It's just such a treat because over the years of knowing each other, we've gone from fierce competitors to true friends," she added.

GOP presumptive nominee Donald Trump tweeted in response to the announcement, saying that the president "wants four more years of Obama - but nobody else does."

Obama just endorsed Crooked Hillary. He wants four more years of Obama—but nobody else does! — Donald J. Trump (@realDonaldTrump) June 9, 2016

Clinton's team swiftly tweeted back to Trump "Delete your account," a frequently-used sarcastic retort on the social media platform.

Obama had stayed conspicuously neutral in his public comments throughout the contentious Democratic primary, although he was widely considered to view his former secretary of state as the best party standard-bearer to continue his policy legacy.

The endorsement comes almost exactly eight years after Clinton conceded to Obama and called for party unity after the hard-fought 2008 Democratic primary.

Obama alluded to that call for unity in the video released Thursday, noting that many skeptics believed that the 2008 primary race left the party divided before Obama went on to comfortably beat Republican nominee John McCain.

And he congratulated Sanders on his campaign and noted that both Sanders and Clinton are "both patriots who love this country and they share a vision for the America we all believe in."

NBC News named Clinton the presumptive Democratic nominee on Monday evening after she secured a majority of Democratic delegates, including the count of superdelegates whom Sanders has derided as Washington insiders.

After significant wins in the California and New Jersey primaries on Tuesday, she had also won a majority of pledged delegates to the Democratic National Convention in July.