New Jersey Gov. Chris Christie endorsed former Massachusetts governor Mitt Romney for president on Tuesday, giving Romney a boost as he tries to consolidate his front-runner status in the race for the GOP nomination.

Christie, who announced last week that he would not seek the GOP nomination, made the endorsement just after 3 p.m. at the Courtyard Marriott in Hanover, N.H., hours before the presidential candidates were to gather at Dartmouth College for the seventh debate of the Republican nomination fight.

“Americans cannot survive another four years of Barack Obama,” Christie said. “Mitt Romney is the man we need to lead America.” Christie added that Romney represents the “best of both worlds” given his experience in the private and public sectors.

Christie said his reasons for backing Romney were his detailed economic plan, his willingness to stand by his health-care plan and the fact that he represents the best chance Republicans have to win the presidency. For his part, Romney called Christie a “real hero.”

In May, Christie praised Romney for a speech in which Romney defended and explained the Massachusetts health-care law enacted when he was governor. “That type of candor is what Americans expect from a serious presidential candidate today,” Christie said at the time.

Sources close to the process said that Romney’s courtship of Christie was a long one, but they provided no details.

The Christie endorsement should provide a major boost to Romney, who has been making the case for weeks that he is the best — and perhaps only — candidate who can beat President Obama in 2012.

Christie, a favorite of tea party and GOP establishment types alike, has emphasized the need for GOP voters to choose someone who can win, rather than someone with whom they agree with on every issue.