Nashua, N.H. -- Rick Santorum may be stuck in the low single digits in New Hampshire polls, but the former senator from Pennsylvania got a boost from a key social conservative on Tuesday. Santorum won the support of activist and former GOP candidate for governor, Karen Testerman.

Testerman -- who previously served as a senior adviser to Rep. Michele Bachmann -- told NBC News by phone she had carefully considered each candidate before settling on Santorum. She served as the Minnesota Congresswoman's communications aide during a controversial staff disbanding in New Hampshire this fall.

"I think [Bachmann] is falling off the charts basically, much to many people's disappointment," Testerman told The Dartmouth earlier this month.

This week, Testerman narrowed her selection to Newt Gingrich and Rick Santorum. Just two days ago, she hosted a campaign event that bore witness to a heated but civil debate between Santorum and a voter on abortion and conception. Today, with just 6 weeks left before the January 10 New Hampshire primary, Testerman threw her support behind a candidate many see as the underdog -- a far cry from Gingrich, who won the influential endorsement of New Hampshire's largest paper, the Union Leader.

Nevertheless, Santorum is thrilled about any support he can get in a state where he receives 1% support, according to a recent survey by University of New Hampshire and WMUR.

“Karen has been a steadfast defender of life, family and the foundational values that make our nation great," Santorum told NBC News in a statement. "Karen understands the magnitude of this election, and her vote of confidence tonight is truly an honor.  I am excited to work with her as we move toward victory in the first-in-the-nation primary.”

Santorum returns to New Hampshire December 2-3 to campaign with Testerman and other state legislative endorsers.