WASHINGTON – Republican presidential hopeful Newt Gingrich landed the endorsement of New Hampshire’s largest newspaper Sunday while rival Mitt Romney earned a dismissive wave, potentially resetting the race in the state with the first-in-the-nation primary.

The backing builds on the former House speaker’s recent rise in the polls and quick work to build a campaign after a disastrous start in the summer. Romney, the former Massachusetts governor who has a vacation home in the state and has been called a “nearly native son of New Hampshire,” absorbed the blow heading into the Jan. 10 vote that’s vital to his campaign strategy.

“We don’t back candidates based on popularity polls or big-shot backers. We look for conservatives of courage and conviction who are independent-minded, grounded in their core beliefs about this nation and its people, and best equipped for the job,” The New Hampshire Union Leader said in its front-page editorial, which was as much a promotion of Gingrich as a discreet rebuke of Romney.

The Union Leader’s editorial telegraphed conservatives’ concerns about Romney’s shifts on crucial issues of abortion and gay rights were unlikely to fade. Those worries have led Romney to keep Iowa’s Jan. 3 caucuses — where conservatives hold great sway — at arm’s length.

At the same time, the endorsement boosts Gingrich’s conservative credentials. He spent the week defending his immigration policies against accusations that they are a form of amnesty. Today, Gingrich takes a campaign swing through South Carolina, the South’s first primary state.

Romney has focused on a long-term strategy that doesn’t lurch from one development to another. Last week, he added Sen. John Thune, a South Dakota conservative, to his list of supporters.

The Union Leader’s rejection of Romney wasn’t surprising. The newspaper rejected him four years ago in favor of Arizona Sen. John McCain, using front-page columns and editorials to promote McCain and criticize Romney.

“It helped McCain a lot because it buttressed the time he spent there. McCain camped out in New Hampshire and was able to make good with The Union Leader,” said Craig Stevens, a spokesman for Romney’s 2008 bid who is not working for a presidential candidate this time.