This is written on the day before the New Hampshire primary, but it still may be a good time to assess the state of the Republican race for the Presidential nomination.

Unless the polls are completely off base, Mitt Romney continues as the clear frontrunner, after having notched a very narrow win in Iowa and a (predicted) strong victory in New Hampshire, a near home state for the former Massachusetts governor.

Mr. Romney is not exactly a beloved figure among many Republicans, but he has quite a few strong points. He looks presidential and is a pretty good debater, and very rarely makes a gaffe. He runs basically even with President Obama in poll matchups, generally a few points better than his main rivals, which gives him a leg up among GOP voters who value electability. He has changed his position on a number of key issues (for example, abortion and health care), but his reputation as a moderate may be a plus rather than a minus in the general election. In addition, Mr. Romney will be able to boast of his business background during the campaign, even as his rivals claim that Bain Capital’s activities were sometimes predatory.

What of the other contenders? One candidate after another has looked to be Mr. Romney’s chief rival, only to fall back.

Donald Trump burst on the scene briefly last spring, only to withdraw in favor of his television pursuits. Texas governor Rick Perry looked to have a compelling story on job creation in his state, but faltered after weak debate performances. Newt Gingrich moved up in the standings after excellent debate performances, but then declined after his opponents’ attack ads emphasized his considerable political baggage. Now the chief rival (leaving out Ron Paul, whose libertarian views are not likely to carry the day) is probably former Pennsylvania senator Rick Santorum, who came within a few votes in Iowa. Mr. Santorum has been running on a pro-family, pro-life platform, with an emphasis on protecting manufacturing jobs.

Is the race effectively over? Much may depend on the next primary, South Carolina on January 21. A Romney victory in South Carolina will clearly propel him in the next major contest, Florida, a big state, on January 31. Assuming Florida is in the bag, Mr. Romney will have swept the first four races (with another likely victory in Nevada on February 4), in states with both moderate and conservative Republicans. This may be a train too fast to stop.

South Carolina, however, may prove to be a bit problematic for Mr. Romney. This is a conservative state and it is possible that this time the considerable number of voters on the right may settle on one of Mr. Romney’s opponents. (Mr. Romney has been benefiting from the many conservative candidates who have been splitting the anti-Romney vote.) In addition, it is possible that some Palmetto State voters may decide they don’t want this race to be over just yet, and decide not to vote for Mr. Romney on that basis. A South Carolina winner other than Mr. Romney would go into Florida as a strong candidate to do well in that state. After Florida, the primaries are a bit more spaced out (for example, there is a three week gap between February 7 and 28), which would further slow Mr. Romney’s momentum.

Still, the race remains Mitt Romney’s to lose and his 81% chance on the Intrade exchange seems only a bit high. He will, however, have to secure South Carolina to lock up an early victory.