A Republican-led committee of the Texas House of Representatives recommended on Thursday that the state’s attorney general, Ken Paxton, be impeached for a range of abuses of his office that the committee said may have been crimes.

The recommendation thrust the State Capitol and its Republican leadership into uncharted political territory in the waning days of the legislative session, setting the stage for the House to hold a vote on impeachment, its first in decades and one of the few ever conducted in the state’s history.

If he is impeached, Mr. Paxton, who has been under a separate criminal indictment since 2015, would be required to step down from his post temporarily while facing trial in the State Senate.

“There’s really no precedent — we’ve really only had two impeachments under the constitution of 1876,” said Mark P. Jones, a professor of political science at Rice University. They include the governor in 1917, who resigned the day before the Senate convicted him, and a district judge who was convicted and removed in the 1970s.

Before the vote, the committee met in an executive session, outside public view.

“Overturning elections begins behind closed doors,” Mr. Paxton said in a post on Twitter that included video of a lawyer from his office arguing against impeachment to reporters in a nearly empty committee room, while the committee’s deliberations were underway.

The extraordinary developments were likely to test the Republican Party in Texas in new and unpredictable ways, at a time when cleavages in the party have increasingly been exposed.

The Texas House is led by Speaker Dade Phelan, a Republican representing Beaumont who is seen as a traditional conservative. In contrast, Mr. Paxton has been allied with the most strident Republican legislators in Texas and with former President Donald J. Trump, in a camp that also includes the lieutenant governor and leader of the State Senate, Dan Patrick.

The vote by the House committee came a day after three hours of detailed testimony on Wednesday from a team of investigators — former prosecutors who were hired by the committee to look into corruption allegations against Mr. Paxton. The investigators described how Mr. Paxton had abused and misused his office to help an Austin real estate developer and donor who also hired a woman with whom Mr. Paxton was having a relationship, and how Mr. Paxton created a climate of fear within the office of the attorney general.

The misdeeds Mr. Paxton was accused of committing rose to the level of possible criminality, the investigators said, including instances of retaliation against people who spoke up.

The committee did not take testimony during its session on Thursday.

The lawyer from Mr. Paxton’s office, Christopher Hilton, told reporters that the committee’s process had been “completely lacking” and called the testimony from Wednesday “false” and “misleading.” He added that the issues raised by the committee had been fully aired during Mr. Paxton’s re-election campaign last year, when he was elected to a third term.

“The 2022 election, the primary and the general was run on these issues, these allegations,” Mr. Hilton said. “The voters have spoken. They want Ken Paxton as their attorney general.”

And, in what appeared to be a preview of a possible legal challenge to the proceedings, Mr. Hilton said that Texas law only allowed impeachment for conduct since the preceding election.

The investigation began in March, after Mr. Paxton, who is also under indictment for securities fraud, had apparently succeeded in putting at least one of his legal troubles behind him. He agreed to a $3.3 million settlement with four of his top aides who had sued him, accusing him of corruption and retaliation.

Mr. Paxton asked the Texas Legislature for the funds to pay the settlement. But Mr. Phelan did not support that use of state money, and said he felt that Mr. Paxton had not sufficiently explained why the state should finance the settlement. The House investigation into the allegations was begun in order to gather information about the funding request, Mr. Phelan’s spokeswoman said.

For two days this week, as the committee’s investigation neared its conclusion, Mr. Paxton waged a war of words and accusations against Mr. Phelan, whom he accused of presiding over a House session last week while drunk. Mr. Paxton based his claim on a video that circulated among hard-right activists who blame Mr. Phelan for the failure of various pieces of conservative legislation in the Texas House.

Much of what was presented to the committee about Mr. Paxton was already known publicly from the allegations made in the aides’ lawsuit. The aides also took their complaints about Mr. Paxton to the F.B.I., which is still investigating.

The vote on Thursday rendered the first official judgment on those allegations, finding them sufficient to begin the process of removing Mr. Paxton from office.

David Montgomery contributed reporting.