Republican Kelly Ayotte is officially entering campaign mode in her quest to keep her U.S. Senate seat.

Ayotte, a first-term senator, is hosting a rally in Manchester on Tuesday to launch her campaign. It’s unclear who she’ll face on the Democratic side; Gov. Maggie Hassan is widely considered the strongest possible challenger but hasn’t said whether she’ll run or seek another term in Concord.

Ayotte is a former state attorney general who won her seat in 2010. As one of the few Republican women in the Senate, Ayotte quickly rose to national prominence and has been suggested as a possible vice presidential candidate.

New Hampshire could prove crucial in the 2016 contest for control of the Senate and outside spending groups are already getting involved in the race.

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