Powerful state Rep. John Zerwas, R-Richmond, is stepping down at the end of September.

Zerwas, chairman of the budget-writing House Appropriations Committee, announced his decision Wednesday afternoon. His resignation is effective Sept. 30.

"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 said in a news release. "I have served under three speakers, and each of them gave me incredible opportunities to lead for which I am grateful."

"Although I am leaving elected office, I look forward to continuing to serve Texas in another capacity," Zerwas added without elaborating.

Zerwas, a doctor, has served in the House since 2007. He was first named the chamber's chief budget writer in 2017 and continued in the post this year under the new speaker, Dennis Bonnen, R-Angleton.

“In his 12 years of public service, John Zerwas has developed a distinguished record of serving his constituents and our state with principle, poise, and an unwavering commitment to statesmanship," Bonnen said in a statement. "His skilled leadership as Chair of Appropriations has played no small role in making Texas the beacon of growth and opportunity that it is today, and his incredible contributions will not soon be forgotten."

After Bonnen's predecessor, Joe Straus, announced his retirement in 2017, Zerwas quickly launched a campaign to succeed the San Antonio Republican. He and other candidates ultimately dropped out of the leadership race about a year later when Bonnen emerged as a consensus choice.

State Democrats are eyeing Zerwas' District 28, in which he won reelection last year by 8 percentage points. Democrat Eliz Markowitz, who ran last year for State Board for Education, has launched a bid for HD-28 in 2020.

The Texas Democratic Party hailed Zerwas' departure as a sign that Texas is the "biggest battleground state."

"That's why State Representative John Zerwas threw in the towel instead of being thrown out of office," party spokesman Abhi Rahman said in a statement.