John D. Anthony resigned from his seat in the Illinois House of Representatives effective June 17, 2016. Local Republican leaders appointed Welter to the vacancy and Welter was sworn in July 9, 2016. He is also the Republican spokesperson for the Committee on Energy & Environment. On January 25, 2021, he was appointed House Republican Conference chairperson for the 102nd General Assembly. As of July 3, 2022, Representative Welter was a member of the following Illinois House committees: • Appropriations - Public Safety Committee (HAPP) • Energy & Environment Committee (HENG) • Family Law & Probate Subcommittee (HJUA-FLAW) • Health Care Availability & Access Committee (HHCA) • Judiciary - Civil Committee (HJUA) • Public Utilities Committee (HPUB) • Utilities Subcommittee (HPUB-UTIL) In the 2022 Republican primary,
Jed Davis defeated Welter for renomination in the newly drawn 75th district. ==Post-legislative career==