Former U.S. Vice President Joe Biden is set to launch his long-awaited campaign for the White House on Thursday with an online video ..

Ending months of speculation on whether he would step forward to challenge President Trump.

Biden, who mounted failed presidential bids in 1998 and 2008, is hoping the political stars align to make 2020 his year..

With early polls placing him in the top ranks … But the moderate Democrat will be up against the LARGEST field to seek the party's nomination in modern times… many of them pushing agendas farther to the left than Biden… on everything from health care to climate change.

But Biden has already run into political headwinds… having to defend himself against allegations spanning decades that he made women feel uncomfortable - with unwanted touching.

Despite the complaints, the 76-year-old is moving ahead, and is hoping his decades of political experience will propel him to the White House.

He was Delaware's longest serving U.S. Senator -- re-elected to office seven times.

And then went on to serve two terms as former President Barack Obama's VP.

And Biden will have to answer for his record.

He chaired the 1991 confirmation hearings for Supreme Court Justice Clarence Thomas and was criticized for not doing enough to protect Anita Hill, who accused Thomas of sexual harassment.

The native of Pennsylvania will also be counting heavily on his long ties to the industrial Midwest… a region critics say Hillary Clinton OVERLOOKED in her failed 2016 bid….

And that helped propel Donald Trump to the White House…