​WASHINGTON – Former HUD head and 2020 candidate Julian Castro lost a key congressional endorsement Sunday to former Vice President Joe Biden.

Rep. Vicente Gonzalez, a Democrat from Castro’s home state of Texas, said on CNN’s “State of the Union” that the Democrats’ large field of 20 candidates needed to be culled.

“I think at this point in time we need to narrow the field and unite as Democrats to defeat Trump in November 2020. And that’s why I believe I’m moving my support to Vice President Joe Biden,” Gonzalez told CNN’s Jake Tapper​.

In a subsequent statement, Gonzalez said Biden “demonstrated statesmanship and leadership” during Thursday night’s debate in Houston, Texas.

Meanwhile, Castro has taken heat for a cheap shot at Biden during the debate.

“Are you forgetting what you said two minutes ago?” the 44-year-old Castro said to the 76-year-old Biden at one point, producing audible gasps in the audience.

When South Bend Mayor Pete Buttigieg chimed in saying “this is why presidential debates are becoming unwatchable,” Castro shot back, “That’s called an election.” ​

Castro also boasted, “I’m fulfilling the legacy of Barack Obama and you’re not,” accusing the ex-vice president of leaving 10 million American uninsured in his proposed healthcare plan.

“That’ll be a surprise to him,” Biden responded.