Julin Castro on Tuesday formally backed Joe Biden for president, following the presumptive Democratic nominees call for police reform in the wake of George Floyds death.
Castro, the former Biden primary opponent, U.S. housing secretary and San Antonio mayor, said in a tweet he was "proud to support" Biden, and a Castro spokesman confirmed he was endorsing the former vice president.
While Castro had called for unity around Biden and vowed to help defeat President Donald Trump, he had not formalized his support for Biden until now.
His brother, U.S. Rep. Joaquin Castro of San Antonio, has not officially backed Biden, though a Joaquin Castro spokesman said in a statement last week that the congressman is "going to do everything he can to make sure Joe Biden beats Trump like a drum."
Both Castros endorsed Elizabeth Warren after Julin Castro dropped his bid at the start of the year.