WASHINGTON - Former Massachusetts governor Mitt Romney won the New Hampshire primary Tuesday, the second state in a row he has carried in his campaign for the 2012 Republican presidential nomination to challenge President Barack Obama in November elections.

Texas Congressman Ron Paul, a liberal,  came second, while former Utah governor Jon Huntsman was third.

"Thank you New Hampshire. Tonight we made history," Romney told well-wishers, flanked by wife Ann, their five sons and extended family. "Tonight we celebrate, tomorrow we go back to work."

It was a start-to-finish victory for Romney in New Hampshire, who led in the polls here throughout the 2012 campaign. Romney owns a summer home in the state, which borders his home state of Massachusetts, where he served as governor from 2003 to 2007.

From here, the candidates go on to South Carolina, the first primary in the South. There, Romney's electoral dominance will not be a such a foregone conclusion. South Carolina is more conservative than New Hampshire, which will give Texas Governor Rick Perry--who campaigned in South Carolina while voters in New Hampshire went to the polls--and former senator Rick Santorum a possible edge.

For both of them, the Jan. 21 primary will be a crucial test of the lasting power of their campaigns. Pressure will be high for former House speaker Newt Gingrich, an ultra conservative, as well, in part because South Carolina borders Georgia, his home state. He did not perform well in the first two primary contests, and his ambitions could be crippled if he fails to garner many votes in South Carolina.

In addition to a more conservative electorate, South Carolina Republicans have developed a reputation for hosting rough-and-tumble presidential primaries. When Mitt Romney arrives there tomorrow, he will face a $3.5 million negative television advertising assault from a pro-Gingrich organization. The first substantial and sustained attack against Romney, it will target his tenure at Bain Capital, the venture capital firm he helped found.