Senate Republican Conference Chairman John Barrasso (R-WY) announced on Tuesday he will run to replace Senate Minority Whip John Thune (R-SD) as the No. 2 Senate Republican.

Barrasso was among the three front-runners for outgoing Senate Minority Leader Mitch McConnell’s (R-KY) role, and his decision to seek the GOP whip role instead means he is now running unopposed. It also leaves the race for McConnell’s job open for a candidate with conservative bona fides to jump in.