Could Romney 'train' be derailed by Gingrich? Perry? Someone new?

The word 'inevitable' is getting tossed around these days when it comes to Mitt Romney and the GOP nomination. But Newt Gingrich remains a real rival, and it's even still possible for a newcomer to enter the contest.

The scenario looks increasingly plausible: Republican voters will ultimately hand their party's presidential nomination to Mitt Romney, even though many of them aren't excited about doing so.

But if the word "inevitable" is getting used a fair amount by political analysts these days, the nomination is hardly a sure thing for the former governor of Massachusetts.

His big assets are that his campaign is well organized, he has had no major missteps, and his rivals have foibles or flaws in the eyes of Republican voters. So it's entirely possible that the train called "Mitt for president in 2012," which essentially left the station after his 2008 candidacy ended, will roll steadily to the nomination.

“The dynamics couldn’t be better for us,” a senior Romney strategist told New York Magazine. “I don’t see any scenario where we’re not the nominee.”

But in a campaign that has been volatile for several months, calling the race over before voting begins may be premature. 

Another scenario, for example, includes a protracted "Newt versus Mitt" battle that pits Mr. Romney against former House Speaker Newt Gingrich, who is now Romney's main rival in polls. 

Another is that one or more candidates who are now further behind catch some momentum in Iowa or New Hampshire, and voters take a second look. That's what Rick Perry, Rick Santorum, and Michele Bachmann are hoping. If things get really complicated, the result could be a "brokered convention" in which no candidates has amassed the needed support before GOP delegates arrive to formally select the nominee.

A third scenario, conceivable if Romney looks vulnerable coming out of Iowa and New Hampshire, is that a new candidate enters the race in time to compete in later primaries. Here again, the outcome could then be drawn-out suspense in the primaries and at the convention.

Here's what one prominent poll shows now.

According to Gallup, Mr. Gingrich is ahead of Romney among registered Republicans nationwide, but just barely. Support for the former House speaker surged last month after the candidacy of businessman Herman Cain collapsed, but over the past three weeks has ebbed to 26 percent.

Some 23 percent of GOP voters say they'd go with Romney, 12 percent with Rep. Ron Paul of Texas, 8 percent with Texas Governor Perry, 6 percent with Representative Bachmann of Minnesota, 3 percent with former Senator Santorum of Pennsylvania, and 1 percent with former Utah Gov. Jon Huntsman Jr.

The idea of a late-entry candidate is surely a wild card, but it's been getting some buzz lately. In a new issue of The Weekly Standard, conservative commentator William Kristol makes a direct appeal to potential candidates now on the sidelines.

"It is a moment ... for others to reflect on whether they don’t owe it to their country to step forward," Mr. Kristol writes. "Now is not a time for leaders to engage in clever calculations of the odds of success, or to succumb to concerns about how they will look if they enter the fray and fall short. Now is a time to come to the aid of our country."

Who is he talking to?

Some prominent Republicans who passed up the chance to run include Indiana Gov. Mitch Daniels, Rep. Paul Ryan of Wisconsin, and New Jersey Gov. Chris Christie (but he has endorsed Romney). 

Former Florida Gov. Jeb Bush is also viewed by some analysts as a potential late-entry candidate, and he happens to have just published an opinion column in The Wall Street Journal singing the praises of free markets. 

The idea of a late-to-the-game newcomer is technically possible, but it is also almost prohibitively daunting. 

He or she would miss key primaries for which deadlines for entry have already passed, except for the option of winning a few delegates through write-in votes. 

Still, more than half the delegates would still be up for grabs (in states with open caucuses or later primaries) for a candidate who entered by early February, writes Rhodes Cook, a political analyst at Sabato's Crystal Ball website.

The challenge: Even a candidate with big name recognition would face the herculean task of building a campaign organization. And voters would be skeptical of candidates who show up so late and, perhaps, are reversing a prior "not running" stance. To some political analysts, it's hard to imagine a serious new candidacy arising absent some significant slip-ups by both Romney and his rivals.

Romney is seeking to bolster his appeal with Republicans with a new ad titled "conservative agenda." 

Gingrich, trying to persuade voters that he's the more conservative alternative, has won some fans but also has struggled – in part because he and Romney have a similar track record on health-care policy.

Does all this leave room for one of the other candidates now in the race?

Many GOP voters view Mr. Huntsman as not conservative enough. Mr. Paul has a sizable following of enthusiastic supporters, but political experts say he would have trouble expanding his appeal, partly because of foreign policy views that differ sharply with the party mainstream. 

Perry, Bachmann, and Santorum are all striving mightily for a strong Iowa finish that could win them a second look from voters. Each has shown a trend of rising support in Iowa (as Gingrich has fallen) in recent polls averaged by RealClearPolitics.com.

But after the Iowa caucuses, attention will shift quickly to New Hampshire, where those three names are far behind. 

Bottom line: It's too soon to call him "inevitable," but Romney retains a position of solid advantage.