US Senator Bernie Sanders suspended his presidential campaign Wednesday, clearing the way for rival Joe Biden to win the Democratic nomination and challenge incumbent Donald Trump in November.

"I have concluded that this battle for the Democratic nomination will not be successful," the leftist Sanders told supporters in a livestream announcing he is dropping out. "Vice president Biden will be the nominee," the 78-year-old added. "I congratulate Joe Biden, a very decent man, who I will work with to move our progressive ideas forward."

Sanders, who challenged Hillary Clinton for the party's nomination in 2016, mounted a formidable challenge to Biden in the 2020 race, becoming the frontrunner early this year and earning the most votes in the first three state-wide contests.

But he was soon eclipsed by a surging Biden, who won the vast majority of the remaining primaries and now holds a commanding lead in the all-important race for delegates who choose the nominee.

Sanders ran an intense, issue-driven campaign, bringing his liberal ideological platform -- including a call for universal health care and a $15 hourly minimum wage -- into the mainstream. "Together we have transformed American consciousness as to what kind of nation we can become, and have taken this country a major step forward in the never-ending struggle for economic justice, social justice, racial justice, and environmental justice," Sanders said.

Several US lawmakers have come out in support of such prescriptions, and Biden himself has shifted leftward to incorporate some Sanders policies, although he has stressed he does not support Sanders's Medicare for All plan. Biden tweeted his thanks to Sanders, hailing him as "a good man, a great leader, and one of the most powerful voices for change in our country."