MURFREESBORO (AP) — Republican state Sen. Bill Ketron is giving up his seat in the Tennessee General Assembly to run for mayor of the state's fifth-most populous county.

The Daily News Journal reports that Ketron said he wants to become Rutherford County mayor to tackle transportation, solid waste and education challenges facing the fast-growing region.

Rutherford County is behind only neighboring Nashville in population growth in Tennessee since 2010. The Census estimates that about 308,000 people lived in the county in 2016, an increase of more than 45,000 over six years.

Ketron is the Senate Republican caucus chairman, the No. 3 leadership position in the chamber. He was an early support of Donald Trump's presidential bid and was the sponsor of a years-long effort to allow wine to be sold in supermarkets.

Ketron unsuccessfully ran for mayor three times in the 1990s and was elected to the Senate in 2002. Current Mayor Ernest Burgess has been in office since 2006, and hasn't said whether he will seek a fourth term next year.

Ketron this year supported Republican Gov. Bill Haslam's transportation funding plan that included the state's first gas tax hike since 1989.

"I viewed the gas tax as critical for infrastructure," Ketron said. "Most of our bridges were built between 1955 and 1965. Most of those bridges were in disrepair across the state."

Ketron has also proposed building a monorail or light rail line along Interstate 24 between Murfreesboro and Nashville.

"We are in gridlock," Ketron said. "It's just going to get worse."

Ketron has advocated for public-private partnerships to help address transit issues in the state.

"Government can't continue to pay for 100 percent of everything," said Ketron, arguing that there's many ways for businesses to profit from investing in mass transit, including advertising and economic development projects. "It's a regional issue."

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Information from: The Daily News Journal, http://www.dnj.com