Republicans see the two seats as potential pickup opportunities in 2014, as both seats have flipped back and forth between the parties in recent cycles, though Shea-Porter is considered more vulnerable as the first district is slightly more favorable to a Republican.
Kuster, however, is the first of the two to have an official opponent, in former state Sen. Gary Lambert, who announced his run for the seat on Wednesday.
During his kickoff event, Lambert touched on typical Republican themes of tax reform and job creation.
According to the New Hampshire Union Leader, he charged that Kuster is "part of the problem" in Washington.
Lambert is thus far the only contender to enter the race, though he could face a primary challenger from the right.
In the first district, state Rep. Pam Tucker (R) told local news outlet WMUR that she plans to challenge Shea-Porter if former Rep. Frank Guinta (R) doesn't make a play for his old seat.
She told WMUR that she's "thinking about" running, and suggested Guinta may be looking into another race.
“I certainly wouldn’t run against Frank, but I understand he is weighing other options now,” she said.
State Sen. Jeb Bradley, considered by Republicans a top contender for either the gubernatorial or Senate race in New Hampshire, announced this week he won't be running statewide in 2014, leaving Republicans without a candidate in either of those races.
He hasn't ruled out a run for Congress, however.
Tucker said that while his decision not to run statewide was "sad ... it certainly has created opportunities for other people so it is important to weigh these options.”