Representative Christian D. Menefee of Texas, a former prosecutor who was sworn into office in February, defeated Representative Al Green in a Democratic primary runoff on Tuesday, according to The Associated Press, after the two were effectively drawn into the same district.

Here are five things to know about Mr. Menefee, 38, of Houston.

1. He is one of the newest members of Congress. Mr. Menefee, who is about 20 years younger than the average House member, campaigned on a message of generational change as he took on Mr. Green, a 78-year-old Democrat known for acts of protest at President Trump’s speeches. “The district is ready for a passing of the torch,” Mr. Menefee said in a recent interview, adding, “I’m ready to take on the torch and lead us into the future.” Earlier this year, Mr. Menefee won a special election runoff in his district. This was his fourth election in seven months.

2. He was the Harris County attorney for five years. Mr. Harris rose to the post, an elected office, in 2020. At 32, he was the youngest person ever elected to the position in Harris County, which includes Houston and is one of the most populous counties in the country. He was also the first African American to serve in the role.

3. He fought Gov. Greg Abbott on cases involving transgender children. Mr. Menefee bucked Mr. Abbott, a Republican, in 2022 after the governor ordered that standard medical treatments provided to transgender adolescents be classified and investigated as “child abuse.” Mr. Menefee vowed that he would not prosecute any such cases. “We don’t believe that allowing someone to take puberty suppressants constitutes abuse,” Mr. Menefee said at the time, describing the governor’s position as a “complete misrepresentation of the definition of abuse.”

4. He was involved in a skirmish over election inspectors in 2022. Mr. Menefee, in his role as county attorney, was critical of the arrival of Texas state election inspectors in Harris County during the 2022 midterm elections. Mr. Menefee argued that the review by the state officials was a politically motivated effort by Republicans allied with Mr. Trump, who had pressed for more scrutiny of the 2020 election. Mr. Menefee’s office sent a letter to the federal government asking that Justice Department monitors join the state inspectors at the polls.

5. He has received support from the crypto industry. Mr. Menefee has received an A grade from Stand With Crypto, an industry group. A crypto-backed super PAC said it had funneled more than $5 million into the race in an effort to defeat Mr. Green, a crypto skeptic who sits on the House committee that oversees financial assets. “I have no control over that,” Mr. Menefee said. He opposes super PACs, he said in the interview, and wants to “regulate them out of existence.”