Updated: 2:43 p.m. ET

New Jersey Gov. Chris Christie is expected to endorse Republican presidential candidate Mitt Romney in the race for the GOP nomination, a coup for Romney that could help him solidify his front-runner status and build an aura of inevitability around his campaign, CBS News and National Journal have confirmed.

Christie is expected to be the "special guest" at a Romney campaign event scheduled for 3 p.m. on Tuesday in Lebanon, N.H.

Christie, a rising star in the Republican Party, was wooed by both conservatives and mainstream Republicans to get into the presidential contest himself. Major GOP donors also courted him at a time when many Republicans reported feeling dissatisfied with their choices. Christie was seen as someone with sufficient political grit to take on President Obama head to head in next year's general election.

The outreach efforts prompted Christie to rethink his earlier decision not to run. But on Oct. 4 he announced he would definitely stay out, citing his commitment to New Jersey as a first-term governor. Since then, Christie's blessing has been sought as one of the biggest plum endorsements of the primary race.

"That's not just an endorsement. It's a super endorsement,'' said Republican consultant Sally Bradshaw, who advised Romney in 2008 and is neutral in the 2012 primary. "He's extremely well respected on fiscal issues, which will define the race. And it helps Gov. Romney and his team make their case that the party needs to come together behind him''

Ron Bonjean, a GOP strategist, said, "It's a move that points to a lot of momentum behind Romney, because those who had wanted Christie to run are now being pointed in Romney's direction. And, to have this come before tonight's (GOP candidate) debate, also just shows where the enthusiasm is going at this point."

Christie's backing could help the former Massachusetts governor lock up the Republican establishment, much of which had been pining for a Christie candidacy, and make inroads with a conservative base that cheered on Christie's tough stance against teacher union's. But most of all, the governor's support is another in a litany of recent markers that indicate Romney's campaign is starting to surge past his rivals.

A new NBC News-Marist poll out Tuesday shows Romney leading the field in both Iowa and New Hampshire. In the Hawkeye State, Romney leads businessman Herman Cain, 26 percent to 20 percent. Rep. Ron Paul of Texas is at 12 percent, while Texas Gov. Rick Perry and Rep. Michele Bachmann of Minnesota are at 11 percent each.

Romney leads among likely Republican primary voters in New Hampshire with 45 percent, trailed by Cain and Paul, both of whom are at 13 percent. Perry is at just 7 percent, and former Utah Gov. Jon Huntsman trails the field with 5 percent. Eight percent of likely primary voters are undecided.

Romney had lagged behind in Iowa, where the first-in-the-nation caucus is dominated by religious conservatives who have not warmed to him. His strategy has been to more or less ignore Iowa and to focus on trying to pull off a big win in New Hampshire.

But in recent weeks, Romney has suddenly become more competitive in Iowa, where a fracturing of the social and religious conservative voting bloc may make it possible for him to eke out a win from less ideological and religion-motivated Republicans.

"You do get the sense Romney is stepping into the front-runner role he has been struggling to capture for quite some time," said Greg Mueller. "Not just based on the polls, but watching the debates."

Christie's support places extra pressure on Perry heading into tonight's televised candidate debate in New Hampshire, where he must try to erase his previous three stumbling efforts. Strategists say there's still time for him to recover, but Christie's endorsement might have begun closing that window.

"Rick Perry still has a great shot as securing the nomination, but this week is really critical for him to pull it off," Bonjean said. "No one is counting him out."

Reporter Beth Reinhard contributed to this report.