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Senate Republicans have a leadership fight on their hands.

Sen. Roy Blunt (R-Mo.) announced Tuesday that he will challenge Sen. Ron Johnson (R-Wis.) for the position of Senate Republican Conference vice-chairman, the No. 5 spot in the chamber’s GOP leadership.

“After receiving encouragement from a number of my colleagues, I’ve decided to run for Senate Republican Conference Vice Chairman,” Blunt said in a statement. “America is facing a critical moment when we’re going to decide who we’re going to be as a nation, and I believe this is a good way for me to continue to contribute to this historic debate.”

The move sets up a battle between two Senate freshmen with vastly different backgrounds.

Blunt is a former seven-term House member who served for six years as his party’s chief vote-counter before stepping down from the spot after Republicans sustained sweeping losses in the 2008 election. The Missouri Republican also serves as the top congressional liaison for GOP presidential contender Mitt Romney.

Johnson, considered a rising star among the freshman class, is a tea-party-backed former businessman who had never previously served in elected office until last year’s Republican sweep.

Johnson announced in September that he planned to run for the vice-chairman spot after Sen. Lamar Alexander (R-Tenn.) set off a leadership shuffle with his announcement that he will resign early next year from his spot as the chamber’s No. 3 Republican.

The Washington Post’s Ben Pershing reported the week after Johnson’s announcement that Blunt was publicly mulling a bid for the vice-chairmanship.

As a congressional veteran, Blunt is well-poised to win the backing of the party’s establishment figures. But Johnson has begun rounding up endorsements in the race: he already has secured the backing of prominent conservatives including Sens. Jim DeMint (S.C.), Lindsey Graham (S.C.) and Tom Coburn (Okla.) as well as fellow freshmen Sens. Marco Rubio (Fla.) and Kelly Ayotte (N.H.).