Sen. Pat RobertsCharles (Pat) Patrick RobertsGOP senators raise concerns about babies on Senate floor Senate passes resolution allowing Duckworth to bring baby on floor Kill off anti-environmental excesses in the farm bill MORE (R-Kans.) and his primary challenger, radiologist Milton Wolf, are exchanging fierce barbs in new ads launched the final weeks of their primary fight.

On Friday, Roberts released an ad hitting Wolf for missing “28 votes on issues important to Kansans” and slamming the challenger as “unethical, irresponsible, unfit for Kansas.” The ad also mentions Wolf’s “unethical x-ray activity,” a reference to reports outlining Facebook postings Wolf made in which he gave off-color commentary on his patients’ x-rays.

Wolf’s campaign launched its own ad, attacking Roberts for a laundry list of "yes" votes, including Kathleen Sebelius's nomination for secretary of Health and Human Services, 11 debt ceiling increases and “Obama’s fiscal cliff tax hike.”

The ad centers around residency questions that have dogged Roberts. It shows Roberts stand-in sitting in a recliner on a golf course, a reference to a report that Roberts no longer lives in his house in Kansas and instead rents a room from donors when he’s in the state.

“Pat Roberts moved to Washington forty seven years ago. Here in Kansas, he rents a La-Z-Boy recliner. At a donor’s house,” a narrator says in the ad.

Similar residency questions have contributed to the defeat of incumbents in the past, most recently former Indiana Sen. Dick Lugar (R). Despite the attacks, Roberts has maintained a solid lead over Wolf and is heading into the final stretch of the race and is heavily favored for reelection.