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."

Treadwell launched his exploratory effort in November. When Gov. Sean Parnell (R) announced recently that he would not run for the Senate seat, it was expected that Treadwell would run.

Treadwell begins the race as perhaps the favorite to face Begich in the general election, though he is expected to face primary opposition.

Among those running or looking at running are state Natural Resources Commissioner Dan Sullivan and 2010 GOP nominee Joe Miller, who lost the general election to the write-in candidacy of Sen. Lisa Murkowski after beating her in a primary. The nomination of Miller would be a big blow to the GOP given he is hugely unpopular in the state.

Treadwell trailed Begich by eight points in a February automated poll from Democratic pollster Public Policy Polling and by 10 points in a January poll from GOP automated pollster Harper Polling. Part of that deficit likely owes to the fact that Begich is more well-known.

Begich is considered one of the most vulnerable incumbents up for reelection in 2014, given his state went for Mitt Romney by 14 points last year.