WASHINGTON, D.C. - U.S. Senator Bob Casey, Jr. (D-Pa.) is endorsing former Vice President Joe Biden for President in 2020, according to a statement released Thursday morning.

The announcement comes at the same time Biden ended months of speculation by formally announcing his bid for the White House in a recorded video released on social media Thursday morning. Biden, 76, becomes the 20th Democratic candidate seeking the party's nomination.

Casey, who mulled a 2020 bid of his own in late 2018, said Biden has the best opportunity to win Pennsylvania and reclaim a state that President Donald Trump won in 2016.

"In order to accomplish the urgent task of defeating President Trump, Democrats must win Pennsylvania," Casey said in a statement Joe Biden can and will win Pennsylvania if he is the Democratic nominee for President."

Biden is scheduled to hold a campaign event at a Pittsburgh union hall Monday afternoon. It's unclear if Casey will also attend the event.

"At this make-or-break moment for the middle class, our children and our workers, America needs Vice President Joe Biden to be its next President," Casey added.

Casey is among just a few Senators who have endorsed 2020 candidates. As of last week, only four others have endorsed a candidate, according to The Hill.