Updated at Aug. 1 at 2:18 p.m. to include Zerwas' new job.

AUSTIN — Rep. John Zerwas, the head of a powerful budget-writing committee in the Texas House, announced Wednesday that he will retire at the end of September. On Thursday, he was announced as the executive vice chancellor for health affairs at the University of Texas System.

"It has been an absolute honor to represent House District 28, and I am proud of what we have been able to accomplish over the last 12 years," Zerwas, a Richmond Republican, said in a prepared statement. "Although I am leaving elected office, I look forward to continuing to serve Texas in another capacity."

Zerwas, who was first elected to the Legislature in 2007, said he had served under three House speakers and was grateful to each for the opportunities they gave him. He said he was "especially proud" of the work accomplished in the most recent session under House Speaker Dennis Bonnen. Zerwas previously served under speakers Joe Straus and Tom Craddick.

His departure will leave a major vacancy in the chamber's leadership. Zerwas, a doctor, served as chairman of the budget-writing appropriations committee for the last two sessions and was seen as a go-to lawmaker on budget and health issues.

After Straus' departure in 2017, Zerwas made a bid to become House speaker before dropping out of the race when momentum began to swing toward Bonnen.

It also will set off a scramble on the Republican side to find his replacement. Zerwas won his Fort Bend County district last year by about 7,000 votes, and Democrats have put it on their list of 2020 targets as they look to flip the House for the first time since 2003.

UT officials celebrated the new hire Thursday.

"I have worked very closely with Dr. Zerwas in the Texas Legislature and have first-hand experience with his longstanding, deep commitment to health care quality and his vast knowledge of the complexities of health care delivery and policies," Kevin Eltife, chairman of the UT System Board of Regents, said in a prepared statement. "He comes to the UT System with a very high regard among colleagues in the medical, business and legislative arenas. I know Dr. Zerwas will bring new insights that will benefit us all, and we're grateful he is willing to make this important public service transition. I could not be more pleased that we were able to recruit him to the UT System."

Zerwas was well respected in the House and had a reputation for working across the aisle. In a tweet following his announcement, Democrat Rafael Anchia of Dallas called him "decent & thoughtful."

Our #txlege colleague @RepJohnZerwas is among the most decent & thoughful members with which I have ever served. He helped make TX a better place. TY amigo for your public service. pic.twitter.com/TQIdoufiyF — Rafael Anchía (@RafaelAnchia) July 31, 2019

Celia Israel of Austin called him a Texas gentleman and said: "This is a big loss for Texas GOP and Texas. Total respect for [Rep. John Zerwas] who was always respectful and helpful to me."

This is a big loss for Texas GOP and texas. Total respect for @RepJohnZerwas who was always respectful and helpful to me in my time in #txlege #texasgentleman https://t.co/1Bi1pz29FO — Celia Israel (@CeliaIsrael) July 31, 2019

Austin bureau reporter Rebekah Allen contributed to this report.