WASHINGTON (Reuters) - U.S. Senator Richard Blumenthal added his voice to Democratic lawmakers worried about Joe Biden's presidential run, telling reporters on Wednesday he was deeply concerned about the president's re-election bid.

"I am deeply concerned about Joe Biden winning this November, because it is an existential threat to the country if Donald Trump wins. So I think that we have to reach a conclusion as soon as possible," Blumenthal told reporters.

Blumenthal added: "And I think, Joe Biden, as the Democratic nominee, has my support."

(Reporting by Katharine Jackson; writing by Susan Heavey; editing by Rami Ayyub)