US President Barack Obama on Thursday endorsed Hillary Clinton to be his successor in a video posted to her campaign's website after she secured the Democratic Party's nomination this week.
"I know how hard this job can be, that's why I know Hillary will be so good at it," he said. "In fact, I don't think there's ever been someone so qualified to hold this office."
Obama had met earlier in the day with Democratic candidate Bernie Sanders and praised him for bringing passion and supporters to the Democratic Party.
Both candidates are "patriots who love this country and share a vision for the America we all believe in," said Obama, noting the primary contest would make the party stronger against Republicans in November elections. He pointed to his own hard-fought challenge against Clinton in 2008 and noted that it didn't damage the party, but rather strengthened it.
"I'm with her. I am fired up and I cannot wait to get out there and campaign for Hillary," Obama said.
He will appear at a campaign rally in Wisconsin with Clinton on Wednesday, her campaign said.
Presumptive Republican nominee Donald Trump blasted Obama's endorsement on his Twitter account.
"Obama just endorsed Crooked Hillary. He wants four more years of Obama — but nobody else does!" Trump tweeted.
Clinton responded with a put-down to Trump on the social media platform: "Delete your account."
Obama had been reluctant to jump into the race until the party's nomination was settled. Spokesman Josh Earnest had repeatedly deflected questions about when an endorsement would come.
Sanders told reporters after meeting with Obama that he would continue to campaign through the primary in the US capital on Tuesday.
He stopped short of endorsing Clinton, but said he will meet with her in the coming days and vowed to do everything he can to defeat Republican candidate Donald Trump.
"I am going to do everything in my power and I will work as hard as I can to make sure Donald Trump does not become president of the United States," Sanders said outside the White House.
White House spokesman Josh Earnest said the conversation was friendly and forward looking.
Obama congratulated Sanders on his "remarkable success" during the Democratic primaries and the men discussed the importance of the general election.
Clinton on Tuesday declared herself the party's presumptive nominee after reaching the number of delegates needed at the party convention to be named its standardbearer in November elections.
Sanders has hung on through the final contests in the hopes of convincing party officials to instead back his candidacy, despite trailing Clinton in the overall delegate count.
At a Sanders rally held in Washington Thursday evening, his supporters hailed the campaign's message and improbable success while acknowledging the end was likely near.
"At the beginning this campaign seemed hopeless, but the grassroots support he's gotten has been amazing," said Celia Byrne, 58, a Washington epidemiologist.
"We recognize reality that he won't likely be the candidate, but we hope his message will still get across."