Former Nebraska treasurer Shane Osborn (R) will enter the Nebraska Senate race, becoming the first GOP candidate to toss his hat in the ring.

"Shane is in the race," campaign manager Dave Boomer told the Lincoln Journal-Star over the weekend. A person familiar with Osborn's decision confirmed the move. Osborn has started a Senate campaign Web site that says he is "committed to serving Nebraskans and to making Washington accountable to hard-working, middle-class families."

Osborn gained celebrity status in the Navy when he piloted a damaged aircraft to a safe landing in 2001. He was elected treasurer in 2006 and served until 2011.

The race for retiring Republican Sen. Mike Johanns's seat appears to be wide open on the Republican side. Gov. Dave Heineman (R) recently announced that he won't run. Neither will Rep. Jeff Fortenberry (R).

Even as the GOP field may grow large and competitive, Republicans remain heavy favorites to hold onto the seat in the conservative-leaning state.