US Vice President Kamala Harris speaks at an event in Washington DC (Photo: Xinhua/VNA)

On his social platform X, Obama vowed he would do everything he could to make sure Kamala Harris wins in November, urging the public to join.

Obama, who served as US president for eight years after winning the election in 2008, is the latest prominent Democrat to endorse Harris' bid after incumbent President Joe Biden announced his withdrawal from the presidential race on July 21.

Earlier, Senate Majority Leader Chuck Schumer and House Minority Leader Hakeem Jeffries, the top two Democrats in Congress, endorsed Vice President Harris for the Democratic nomination for president.