CEDAR RAPIDS, Iowa -- By closing the door on a 2012 presidential bid, Gov. Chris Christie may have opened the window on Mitt Romney's chances of winning the Republican nomination.

Even though Sarah Palin continues to flirt with jumping into the GOP nomination race, the Republican field now appears set, said Iowa GOP strategist Doug Gross.

That, according to Donna Hoffman, an associate professor of political science at the University of Northern Iowa, is likely to help Romney establish himself as the candidate who will run best against President Barack Obama.

He may not win over all of the "none of the above" Iowa Republicans before the first-in-the-nation precinct caucuses, Hoffman said about Romney, "But he survived the Bachmann onslaught and he's surviving the Perry onslaught, so Romney may be the only game in town for mainstream Republicans."

And that's where a Christie candidacy may have done the most damage to Romney's prospects, according to Gross. Christie's appeal would have been to the same Main Street Republicans as Romney but as a fresher, more aggressive challenger to the incumbent president.

To a large degree, Gross said, it sets up a mirror image of the 2008 GOP contest when there was one social conservative left standing after the Iowa GOP straw poll. Four years ago, Romney and other mainstream Republicans divided their support, allowing Mike Huckabee to win the Iowa precinct caucuses.

This time there are multiple social conservatives, leaving Romney and Texas Gov. Rick Perry to fight over mainstream Republicans, he said.

It may be premature for Romney to claim victory, according to Tim Hagle, who teaches political science at the University of Iowa. There may be time for Rep. Michele Bachmann, R-Minn., and Perry to get back on track, and pizza magnate Herman Cain is climbing in the polls.

Hagle agrees with Hoffman that Christie's departure will not have a major impact in Iowa. Despite entreaties to Christie by well-heeled Iowa GOP donors, Hagle doesn't know how deep the support for the New Jersey governor was in Iowa.

"His name didn't pop up in polls like Sarah Palin's, so we don't know how much people, especially Iowans, really wanted Christie to jump into the race," Hagle said.

For Iowa Republicans waiting for Palin to get into the race, Christie's exit "doesn't make any difference to Gov. Palin," according to Peter Singleton of Organize 4 Palin. "It doesn't make any difference to her grass roots."

Christie has done a good job of making a "rhetorical case for limits on government, but his record is not that conservative," Singleton said.

Given that Christie probably is more liberal than any of the current GOP presidential hopefuls, Hagle believes his appeal to the party's base was as someone who could defeat President Obama.

If that's the case, Iowa Republicans may shift to Romney for the same reason.