Democrat incumbent Evalyn Merrick plans to seek a recount after losing her seat by 12 votes.
She said a dozen votes was too tight a margin not to ask that it be reviewed.
"I owe it to the voters," she told NHPR.
Merrick had 3,253 votes compared to Republican Leon Rideout who had 3,265, according to a tally compiled by the Associated Press.
The official tally by the New Hampshire Secretary of State is not yet available.