It was a watershed Thursday for Mrs Hillary Clinton as Democratic heavyweights, including United States President Barack Obama, endorsed her candidacy for president while calling for unity to defeat Republican presumptive nominee Donald Trump.
Mr Obama was the first to endorse his former secretary of state, asking voters to unite behind her and fight for American values. He was followed by Vice-President Joe Biden and Massachusetts Senator Elizabeth Warren, who declared herself "ready" to ensure that Mrs Clinton is the next US president.
Ms Warren, a favourite of the party's progressives, is seen as a possible running mate for Mrs Clinton, who has previously said the US may be ready for a two-woman ticket.
Giving his stamp of approval through a video launched on Mrs Clinton's campaign website, Mr Obama said: "I don't think there has ever been someone so qualified to hold this office. She's got the courage, the compassion and the heart to get the job done."
Though Vermont Senator Bernie Sanders is still in the race, Georgia State University political science associate professor Daniel Franklin believes that the top-level endorsement "signals the end of the nomination process to the Democratic Party, to Mr Sanders and his supporters as well".
"I know how hard this job can be. That's why I know Hillary will be so good at it," Mr Obama says in the video. "In fact, I don't think there's ever been someone so qualified to hold this office. She's got the courage, the compassion and the heart to get this job done."
Political experts also say the endorsements have come at an opportune time, with the Clinton campaign on an upswing after winning important primary contests such as in California on Tuesday.
"Clinton's campaign is having a fantastic week, while Trump's campaign is having a difficult one. This might be an effort by Obama to cement the Democrats' recent momentum and close out a Trump comeback," said University of Wisconsin-Madison political science professor Barry Burden, who is also director of the Elections Research Centre at the university.
Dr Franklin said that because Mr Obama is "exceptionally popular among most Democrats", his endorsement would help Mrs Clinton hold on to and energise her base.
Reacting to the news, Mr Trump tweeted: "Obama just endorsed Crooked Hillary. He wants four more years of Obama - but nobody else does."
The endorsements came after Mr Obama met Mr Sanders at the White House, where they discussed opportunities to ensure that the party remained "diverse, vibrant and inclusive", said White House press secretary Josh Earnest.
He added at his daily press briefing that there was "a lot of agreement" between the two men about the highest priorities that the next president will have to grapple with, including economic opportunities for the middle class.
After the meeting, Mr Sanders gave a speech, signalling his willingness to work with Democrats against Mr Trump, though he did not formally withdraw from the race.
Hoping to unite supporters, Mr Obama, in the video, said both Mrs Clinton and Mr Sanders are "patriots that love this country" and "share a vision for the America that we all believe in".
"If we all come together in common effort, I'm convinced we won't just win in November, we will build on the progress that we've made and we will win a brighter future for this country that we love," he said.
Mr Obama is expected to hit the campaign trail next Wednesday, joining Mrs Clinton in Wisconsin, after she makes stops in Pennsylvania and Ohio.
Experts say Mr Trump is making a bid for these states, hoping to win them over come November and secure a victory for his party.
The mid-western state of Wisconsin is of particular interest to both sides not only because it is often a battleground in presidential elections, but also because both Mr Trump and Mrs Clinton lost their primaries there. "The Democrats would like to prevent the Trump campaign from making inroads in key mid-western swing states by emphasising his (Mr Trump's) vulnerability," said Dr Burden.