Sununu announced Wednesday he would not be a candidate, The Hill reported, a decision that opens the door for other Republicans in New Hampshire. The only announced candidate for the seat so far is Democratic Rep. Paul Hodes.
After serving three terms in the House, Sununu, the son and namesake of a former New Hampshire governor and White House chief of staff, narrowly defeated Gov. Jeanne Shaheen for the Senate in 2002. In a rematch, Shaheen beat him 52 percent to 45 percent last year.
Several Republicans have shown interest in running, including Fred Tausch, a businessman who has hired some of Sununu's former staff. Other possible candidates include New Hampshire Attorney General Kelly Ayotte, former Rep. Charlie Bass and Ovide Lamontagne, who lost to Shaheen in the 1996 gubernatorial race.
New Hampshire, once a state that almost never elected Democrats statewide, has been leaning toward the party in recent years.