Dan Sullivan initially led Mark Begich by about 8,100 votes last week, and when state officials counted absentee and questioned ballots yesterday, the results indicated that Begich could not overcome Sullivan's lead.
The Alaska seat had been considered key to the Republicans' hopes of taking control of the US Senate, but that was accomplished on election night with the Republican sweep.
The Republicans now have 53 seats in the 100 seat chamber with one seat still to be decided in a runoff election.
He also attracted some star power to the state, with Texas Sen.
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Ted Cruz, a favorite of the ultraconservative tea party movement, and 2012 Republican presidential nominee Mitt Romney rallying support for Sullivan in the waning days of the hotly contested race.
Sullivan pledged to fight federal overreach, talked about the need for an energy renaissance in the U.S. And at seemingly every opportunity, sought to tie Begich to President Barack Obama and Senate Democratic Leader Harry Reid, who are unpopular in Alaska.