New Hampshire's gubernatorial election could be a referendum on gay marriage.

Gov. John Lynch (D) announced Friday he would seek an unprecedented fourth term. He came under attack recently from national conservative groups for signing a gay marriage bill into law last year.

The National Organization for Marriage (NOM) sponsored a $200,000 TV ad buy that started running on Tuesday, according to the Nashua Telegraph. The ad hits Lynch on supporting gay marriage but also on taxes and spending.

"New Hampshire residents were shocked last year when they learned that Gov. Lynch had been lying to them about his position on gay marriage," Brian Brown, NOM's executive director, told the paper. "Even though he promised voters when he ran for office that he did not support gay marriage, Lynch signed same-sex marriage legislation into law."

"The job isn't done," Lynch said in announcing his decision to run again.

New Hampshire's governors serve two-year terms – none have been elected to a fourth.

The state's Republican Party called it an attempt to "cling to power."