REUTERS/Jim Bourg

Romney shaking hands with supporters in Manchester, N.H., on Tuesday night.

WASHINGTON — Mitt Romney was supposed to win the New Hampshire primaries, and he did so easily on Tuesday night, with a double digit victory over Ron Paul.

Romney is now two-for-two in the Republican presidential nomination process, having won the Iowa caucuses by a whisker last week. He’s on solid footing in the next couple of early-voting states as well. In South Carolina, which holds its primaries on Jan. 21, polls give him an average of an 11-point lead. In Florida, it’s at 6 points.

The only hope for the candidates who have spent the last several months trying to position themselves to the right of Romney is to gain dramatically more support in South Carolina than they have so far, but history shows that it might already be too late for them to stop him.

For conservatives like Iowa runner-up Rick Santorum and the under-performing Rick Perry (who will get no more than 1 percent of the vote in New Hampshire), the South Carolina primaries are a critical event. South Carolina’s Republicans more closely resemble Iowa’s (social conservatives for whom issues like abortion and gay marriage are nearly as important as economic issues), meaning the candidates who performed well there have a much better shot than in New Hampshire.

Republicans there indentified themselves as much more moderate than in either Iowa or South Carolina, and the demographics reflect that: there are far more evangelical voters or Tea Party-aligned Republicans in South Carolina than New Hampshire. Santorum does well with this audience, and Perry has targeted it as well. If social conservatives coalesce around one or other, they’ll give Romney a run for his money; if they split the vote, Romney wins another the state and the two will have missed their shot to impact the race to any great degree.

Of the non-Romneys, Newt Gingrich has the highest favorables and seemingly the best shot of squeezing some of Romey’s support away from him. He’s popular in both South Carolina and Florida, which votes on Feb. 1, and he’s got a well-funded SuperPAC that has already targeted Romney. But he’s fallen considerably after his brief surge in the polls last fall, besieged by a SuperPAC that has supported Romney. If Gingrich can recover from those attacks and launch good ones of his own, he could threaten Romney going forward.

Ron Paul, meanwhile, finished third in the Iowa caucuses and second in New Hampshire. His supporters are some of the most passionate in politics, but at the moment there just aren’t enough of them to challenge Romney in South Carolina. He’s polling around 10 percent there, 20 points below Romney. He’s not likely to lose any of those supporters, so the question is whether undecided voters can see him as a viable alternative candidate

If none of the other Republicans can knock off Romney, and soon, it might not be too early to call the Republican nomination race for the former Massachusetts governor. Romney is the first Republican since 1976 to win both the Iowa caucuses and the New Hampshire primary. Winning two of the first three voting states is seen as incredibly important — the eventual Republican nominee has won two of the three in every election since 1980. Every one of them won South Carolina and either Iowa or New Hampshire

History tells us momentum will be firmly on Romney’s side if he wins in on Jan. 21. A sweep of Iowa, New Hampshire and South Carolina will only solidify Romney's inevitability.

Devin Henry can be reached at dhenry@minnpost.com. Follow him on Twitter: @dhenry