Republican Mitt Romney, looking to close the deal in the early primary state of New Hampshire, picked up an important endorsement on Sunday from U.S. Sen. Kelly Ayotte.

Ayotte was elected in 2010 from New Hampshire as part of big Republican gains in Congress, and is the top Republican elected official in the state. Her campaign had support from, among others, former vice presidential candidate Sarah Palin.

Romney has won nearly every major Republican endorsement in New Hampshire so far, and has led in Republican polls in the state by a wide margin for almost two years.

On Friday, though, a survey by Magellan Strategies showed former House Speaker Newt Gingrich drawing within two percentage points of Romney.

New Hampshire holds its 2012 Republican primary election on Jan. 10. The vote is regarded as one that Romney must not just win, but win convincingly.

The former Massachusetts governor has stepped up his campaigning in the state, where he owns a house. On Sunday he and Ayotte appeared at a rally in Nashua, her home town.

Ayotte was one of Palin's Mama Grizzlies in 2010, and is a former state attorney general.

In a statement, Ayotte cited Romney's experience as a businessman and governor, and his excellent presidential debate performances in her decision to endorse him.

Romney has also been endorsed by major New Hampshire figures like former Republican Gov. John Sununu and former U.S. Sen. Judd Gregg.