WASHINGTON — Representative Joaquin Castro, Democrat of Texas, has made no secret of his desire to see President Trump out of office: He has been one of the most vocal critics of the president’s immigration policies and voted to impeach him the first time.

Now Mr. Castro, a Harvard-educated lawyer who sits on the Intelligence Committee, will be a part of the prosecution against Mr. Trump as an impeachment manager in the Senate trial.

In his remarks on the House floor on Wednesday before the vote to impeach Mr. Trump, Mr. Castro described the attack on the Capitol and then asked his fellow lawmakers: “What do you think they would have done if they had gotten in? What do you think they would have done to you? And who do you think sent them here?”

He concluded that impeachment was the only option.

“If inciting a deadly insurrection is not enough to get a president impeached, then what is?” Mr. Castro said. “All of us must answer that question today.”

A San Antonio native and second-generation Mexican-American, Mr. Castro served in the Texas Legislature before winning a bid for a congressional seat in 2012. Named by his peers as president of the freshman congressional class in 2013, Mr. Castro soon secured a spot on the Intelligence Committee and in leadership roles in the Hispanic Caucus.

As a member of the committee in 2019, Mr. Castro sat in on both the initial closed-door hearings during Mr. Trump’s first impeachment inquiry and then the public questioning of witnesses before the drafting of impeachment articles. He also serves on the House Foreign Affairs Committee.

Mr. Castro, who led the Hispanic Caucus during the 116th Congress, has loudly opposed Mr. Trump’s immigration policies, leading numerous delegations to the southwestern border and condemning what he has called cruel and dehumanizing policies.

Mr. Castro’s identical twin brother, Julián Castro, ran for the Democratic presidential nomination with his support in 2020. After Julián Castro dropped out, Mr. Castro endorsed Senator Elizabeth Warren of Massachusetts before supporting Joseph R. Biden Jr.