New Mexico Sen. Tom Udall (D) won, while his cousin in Colorado was defeated.
The GOP state senator defeated gaffe-prone Rep. Bruce Braley (D).
The GOP secured a Senate majority before midnight.
It's a huge win for the GOP, as Tillis had trailed Hagan for much of the race.
The group launched an ad Tuesday night hitting Landrieu on energy issues.
Republican Scott Brown is holding out for final returns in heavy Republican counties.
Alexandra Jaffe 11/04/14 11:08 PM EST
Republican incumbent beats back challenge from Independent Greg Orman.
Sen. Brian Schatz (D-Hawaii) won reelection Tuesday against Republican Campbell Cavasso, according to CNN.
The race leaned in Schatz’s favor. He was first appointed to his Senate seat in December 2012 after longtime Sen. Daniel Inouye (D-Hawaii) died.
Sen. Jeff Merkley (D-Ore.) easily won a second term Tuesday, after what initially appeared to be a challenging race.
Multiple networks project Perdue will win without having to go to a runoff election.