LAWRENCE, Kan. (AP) — Kansas Sen. Pat Roberts won’t debate tea party challenger Milton Wolf ahead of the state’s Aug. 5 Republican primary.

The Lawrence Journal-World reports that Roberts executive campaign manager Leroy Towns said Friday that Wolf has failed to outline positions beyond what Towns called vague rhetoric and false attacks on the senator.

Wolf campaign spokesman Ben Hartman said it’s unbecoming for Roberts to duck debates and noted that Roberts previously had promised publicly to have them.

The 78-year-old Roberts is seeking his fourth, six-year term in the Senate. Wolf is a 43-year-old radiologist making his first run for public office.

Two lesser-known candidates also are on the GOP ballot. Shawnee County District Attorney Chad Taylor and Lawrence attorney Patrick Wiesner are seeking the Democratic nomination.