OVERLAND PARK, Kan. (AP) — Wisconsin Congressman Paul Ryan is urging Kansans to back Republican Sen. Pat Roberts in a tight re-election race, saying the three-term incumbent isn’t a “rubber stamp” for President Barack Obama.

Appearing Friday at a hotel in the Kansas City suburb of Overland Park, Ryan is the latest in a string of high profile Republicans to stump for the 78-year-old senator. Attention on the race intensified when the Democratic candidate dropped out, improving independent candidate Greg Orman’s odds.

Republicans need a net gain of six seats to recapture a majority and had always counted on Roberts winning re-election. He’s seeking to unify the GOP behind him by highlighting his opposition to Obama and Senate Democratic leader Harry Reid. Orman says he’ll caucus with whichever party has a clear majority.