Roberts leads every potential Democratic challenger tested in the survey from Democratic firm Public Policy Polling, but less than half of Republicans polled, 42 percent, say they would re-nominate him to the Senate. Thirty-four percent say they'd rather back someone "more conservative" than Roberts, while 24 percent say they're not sure.

Overall, a full 41 percent of Kansans polled say they're unsure of how they feel about the Senator's job approval. Thirty-one percent approve, and 28 percent disapprove.

However, Roberts holds a double-digit lead over all potential Democratic and Republican challengers. No Republicans have yet indicated an interest in the race, and Roberts likely has the Republican bona fides to dissuade any lukewarm contenders from entering the race.

The PPP survey was conducted among 1,229 registered Kansas voters from Feb. 21-24, and has a margin of error of plus or minus 2.8 percentage points overall, and 3.6 percentage points for the Republican-specific sections.