Illinois state Sen. Killard says he'll resign in July before becoming chairman of the Regional Transportation Authority.
The Hinsdale Republican was elected to the post Wednesday. He said he needs time to transition into his new position and calls the exit from more than 20 years in the legislature "bittersweet."
He made two unsuccessful Republican primary bids for governor.
Dillard -- who is also an attorney -- said he has already begun work with the RTA. The position officially takes effect Aug. 1.
The RTA provides financial oversight for the Chicago Transit Authority, Metra and Pace. He said he has a unique perspective in understanding the region's transportation issues.
Dillard says he doesn't know who will be appointed to take his seat after he officially resigns.