Joe Biden and Kamala Harris
Joe Biden and Kamala HarrisReuters

US Senator and former Democratic presidential candidate Kamala Harris announced on Sunday she's endorsing Joe Biden for president.

"When I started my run for president, I said America needs a president who reflects the decency and dignity of the American people; a president who speaks the truth; and a president who fights for those whose voices are too often overlooked or ignored. I still believe that to this day. That is why I am proud to announce I am endorsing my friend, Vice President Joe Biden, for President of the United States," Harris said in a statement quoted by CNN.

The California Democrat, who ended her 2020 presidential campaign in December 2019, also posted the announcement in a video on her Twitter account. She added that she would be in Detroit Monday to campaign with Biden.

Biden on Sunday morning thanked Harris for the endorsement, saying "from our family: thank you."

"Kamala — You've spent your whole career fighting for folks who've been written off and left behind — and no small part of that alongside Beau. From our family: thank you," the former Vice President said in a retweet of her endorsement.

Harris dropped out of the presidential race in early December due to financial pressures and after months of polling in single digits. Biden later said he would consider her as a potential running mate.

The endorsement from Harris comes as a string of former 2020 presidential contenders have thrown their support behind Biden. These include Minnesota Sen. Amy Klobuchar, former South Bend, Indiana mayor Pete Buttigieg, and former Texas Rep. Beto O'Rourke.

Former Secretary of State John Kerry has also endorsed Biden. Kerry was the Democratic presidential nominee in 2004, losing the election to President George W. Bush.