At the moment, Republicans are gearing up to take back several seats they lost in 2006. Allen is running for his old seat in Virginia, while Rep. Denny Rehberg (R-Mont.) is taking on Sen. Jon Tester (D). Sen. Claire McCaskill (Mo.), another first-term Democrat, has already drawn a couple of candidates, including former state Treasurer Sarah Steelman and former House candidate Ed Martin.
Other Democratic seats could be vulnerable as well. If Sen. Ben Nelson (D-Neb.) runs, he will likely face Attorney General Jon Bruning (R), who is amassing a grass-roots campaign team to compete in all corners of the state. Republicans are also waiting on former Rep. Heather Wilson in New Mexico and former Hawaii Gov. Linda Lingle, both of whom would give the party a chance for victory.
Former Sen. Scott Brown, R-Mass., candidate for U.S. Senate in New Hampshire, holds his hand over his heart during the singing of the national anthem as he waits to take the stage for his town hall campaign rally with Sen. John McCain at the Pinkerton Academy in Derry, N.H., on Monday, Aug. 18, 2014.