Biden has begun to roll out a steady stream of endorsements as the first nominating contests in Iowa and New Hampshire draw closer and as the field narrows further with New Jersey Sen. Cory Booker's announcement Monday that he would drop out of the 2020 race. The former vice president is among the top contenders for the Democratic nomination, along with South Bend, Ind., Mayor Pete Buttigieg and Sens. Bernie Sanders (I-Vt.) and Elizabeth Warren (D-Mass.).

Earlier Monday morning, Rep. Collin Allred, who represents a swing district in Texas, became the 10th black member of Congress to endorse Biden. POLITICO reported over the weekend that a group of vulnerable House Democrats were coalescing behind Biden, triggered in part by concerns about the down-ballot impact that progressive Sens. Bernie Sanders (I-Vt.) or Elizabeth Warren (D-Mass.) could have next November.

Maloney dismissed accusations from the left that Biden is not progressive enough, arguing the former vice president has a demonstrated a "record of achieving progressive change that anyone would be proud of." The congressman, who is openly gay, singled out in particular Biden's "early and critical role in the fight for marriage equality," which he said "meant a great to deal to me personally."

Maloney’s endorsement of the former vice president comes after he initially backed former Rep. Beto O’Rourke (D-Texas) early in the race last year. O’Rourke, who entered the race with a splash and was expected to be among top candidates in the crowded field, fizzled out and ended his campaign in November.

While Maloney on Monday called O’Rourke, who ran further to the left than the more moderate Biden, a “close personal friend,” he said that O'Rourke's exit allowed him “to focus on who I think would be the strongest candidate,” who he argued was “clearly” Biden.