Josh Marshall begins to think so:
Public Policy Polling is currently in the field in [South Carolina]. And they’ve just tweeted a few polling morsels from there first night of polling. And the first night shows Mitt Romney ahead by 10 points in the state, with Gingrich and Santorum battling for second. It seems very likely that Romney will win convincingly in New Hampshire. If he then goes on to score a clear win in South Carolina, that would likely be pretty much it in terms of a real battle for the nomination.
A new CNN poll has Romney at 37%, Santorum at 19%, and Gingrich at 18% in South Carolina:
Romney is getting his share of born-again Christians (35%), Tea Party supporters (32%) and self-described conservatives (37%). This is, however, South Carolina, notoriously one of the nastiest political battlefields in the U.S., and the anonymous backstabbing, radio spots, Church fliers and Super PAC attack ads have yet to saturate the state. And a 49% plurality of likely voters said they are still open to changing their minds. A New Hampshire surprise could tilt expectations. Santorum might just need more time. But for now, everything’s coming up Romney.
The news has to be encouraging to both Romney and Santorum. Romney was not expected to do well in South Carolina, but his numbers have improved quite a bit over the last three weeks, and two-thirds of voters in this poll expect him to win the nomination, while 45% believe he’s the strongest candidate to beat Obama in the fall. Only 16% believe that of Santorum, which means his support outstrips his perceived viability. A second-place finish in New Hampshire might improve that number and perhaps add more to his support, but that may come at the expense of other conservatives in the race rather than Romney.
(South Carolina poll of polls from TPM.)