Former US President Barack Obama on Tuesday said that he is endorsing Joe Biden, his former deputy, for the White House.

Taking to Twitter, Obama posted a video in which he talked about Biden’s leadership, saying, “That’s why I’m so proud to endorse Joe Biden for president of the United States”.

The former president further said, “Choosing Joe to be my vice president was one of the best decisions I ever made, and he became a close friend”.

“And I believe Joe has all the qualities we need in a president right now”, Obama added.

In response to Obama’s tweet, Biden retweeted the video, saying Obama’s endorsement “means the world” to him.

“We’re going to build on the progress we made together, and there’s no one I’d rather have standing by my side,” the former US vice president said.

Earlier on Monday, former White House candidate Bernie Sanders endorsed onetime rival Joe Biden for president and said that it was time to unite in the effort to defeat Donald Trump in November.

The two veteran politicians, who each spent the past year battling for the Democratic nomination, appeared together by split-screen on Biden’s livecast.

The Democratic National Committee has postponed the party’s presidential nominating convention in Milwaukee, Wisconsin, to August 17, the week before the Republican Party’s convention, scheduled for August 24 to 27 in Charlotte, North Carolina.

Sanders struck a unifying tone on Monday, telling viewers “it’s imperative that all of us work together.”

The deadly coronavirus pandemic has forced a suspension of all in-person political campaigning, as most of the nation remains under stay-at-home orders — including Biden and Sanders, who appeared online from their homes.

Trump’s re-election campaign said in a statement that Biden has “had to adopt most of Bernie’s agenda” — policies that Trump has branded socialist.

“President Trump’s supporters will run through a brick wall to vote for him. Nobody is running through a brick wall for Joe Biden,” Trump 2020 campaign manager Brad Parscale said in a statement.

Trump’s approval rating has ticked up in the last few weeks of the pandemic, even as the US death toll soared past 20,000, a global high.

But in a series of polls conducted this month, Biden leads Trump in head-to-head general election matchups by an average of 5.9 percent, according to the RealClearPolitics website.

The 2020 US presidential election is scheduled for Tuesday, November 3.

(With inputs from agency)