Alaska Lt. Gov. Mead Treadwell (R) announced Tuesday that he will officially challenge Sen. Mark Begich (D) in 2014, transitioning from an exploratory committee to a full-fledged campaign.

"This intense exploratory effort has convinced me that I have the support necessary to build a winning campaign," Treadwell said on his Web site. "Today I’m taking the next step by announcing that I will not seek re-election as Alaska’s lieutenant governor and have begun to file documents required as a candidate for the United States Senate in 2014."