Barack Obama has endorsed Vice-President Kamala Harris to be the Democratic presidential nominee, ending days of speculation over whether he would support her.

Former President Obama and ex-First Lady Michelle Obama said in a joint statement that they believe Harris has the “vision, the character, and the strength that this critical moment demands”.

The US vice-president has already secured the support of a majority of Democratic delegates, setting her on course to become the official nominee at the party convention in August.

The Obamas said in Friday’s statement that they could not be “more thrilled to endorse” Harris. They vowed to do “everything we can” to elect her.

“We agree with President Biden. Choosing Kamala was one of the best decisions he’s made. She has the resume to prove it,” said the couple’s statement.

They cited her record as California’s attorney general, a US senator and then vice-president.

“But Kamala has more than a resume. She has the vision, the character, and the strength that this critical moment demands.

“There is no doubt in our mind that Kamala Harris has exactly what it takes to win this election and deliver for the American people. At a time when the stakes have never been higher, she gives us all reason to hope,” the statement read.

The statement was accompanied by a video of Harris taking a phone call from the Obamas in which they pledge their support.

“Oh my goodness. Michelle, Barack, this means so much to me,” Harris said.