Former Sen. Bob Smith (R-N.H.) on Sunday told New Hampshire news outlet WMUR that he will challenge Sen. Jeanne Shaheen Jeanne ShaheenOvernight Defense: Trump gets briefing at Pentagon on ISIS, Afghanistan | Senate panel approves five defense picks | Senators want Syria study in defense bill Gore wishes Mikulski a happy birthday at 'Inconvenient Sequel' premiere Senators ask for Syria policy study in defense bill MORE (D-N.H.) in the upcoming election.

Shaheen, elected to the Senate in 2008, is up for reelection in 2014. Smith told WMUR that he likes Shaheen “as a person,” but “couldn't disagree more with her politics."

Smith was elected to the Senate in 1990 and represented New Hampshire in the Senate until he lost the 2002 Republican primary to Sen. John Sununu.

Smith told WMUR that he will be moving to New Hampshire full time and launch his campaign in January, as well as filing paperwork to form his committee campaign in the coming days.

The Republican field for 2016 includes former state Sen. Jim Rubens and activist Karen Testerman, and former Sen. Scott Brown (R-Mass.) was rumored to be considering entering the race.

--This report was updated at 5:15 p.m.