In 1996 Lamar Alexander steamed into New Hampshire after a respectable third-place finish in the Iowa caucuses, with hopes that a first or second place finish might pave his way to the Republican nomination. He fell just short. Pat Buchanan won the primary with 27 percent of the vote, Bob Dole finished second with 26 percent and Alexander was third with 23 percent. If Alexander had won just 7,591 more votes — which would have amounted to 0.84 percent of the votes cast later that year in Florida's Republican primary — he might have ended up as the chief opponent of Pat Buchanan, and as such would have won the Republican nomination. He would not have beaten Bill Clinton in November, but he might have run well enough to make him a strong candidate for the Republican nomination in 2000 and the 43rd president of the United States. Don't think he has never mulled over this counterfactual.

And don't think it hasn't crossed the minds of the Republican candidates who according to current polling have between are getting between 10 and 15 percent in New Hampshire and thus have plausible hopes of finishing second or third behind Donald Trump—Marco Rubio (15 percent), John Kasich (13 percent), Ted Cruz (13 percent) and Jeb Bush (10 percent). Especially Rubio, whose close third place finish in Iowa helped get him a bump in New Hampshire polls up through the debate on Saturday night.

What has happened since then? You can encounter several theories when you move around New Hampshire. Theory A is that Chris Christie's criticism of Rubio for giving pre-packaged lines followed by Rubio's repeating the same line three times has stopped Rubio's momentum and moved voters committed to or considering him to other candidates. Theory B is that this hasn't had much effect and that Rubio is still better positioned than anyone else to finish in second place (Donald Trump polls so far ahead that no one, not even well-disciplined campaign staffers, is predicting that he won't win).

Advocates of Theory A cite canvassing results by other campaigns, but this may or may not be indicative. Voters encountered on doorsteps, sidewalks or mall parking lot by a worker for one candidate don't usually say they're supporting another. Theory A boosters also cite poll results which suggest that Rubio hasn't made any gains since Saturday. But polling typically stops at 9 p.m., and the Saturday debate began after 8 p.m. Not many respondents are likely to have seen it. And any Sunday polling took place on Super Bowl Sunday, a day (like Christmas or Thanksgiving) which pollsters usually avoid because of the difficulty of obtaining a valid sample. As for Monday evening polling, is anyone even bothering? Campaigns can't do anything with the information, and the rest of us will have more definitive information when the polls close Tuesday.

My own view is that voters are less concerned about the canned nature of his response than are journalists. Reporters have to listen to candidates over and over, and get tired of hearing the same thing over and over. (John Edwards used to utter the exact same speech, word for word, at every stop.) Voters, even attentive New Hampshire voters, haven't heard the candidates repeatedly and often aren't paying close attention when they do. They don't mind candidates repeating themselves. Christie's attack and Rubio's response may have convinced some voters that Rubio, at 45 and with just a thin record in his first term in the Senate, is not qualified for the presidency. But I don't think they were as devastating as some pundits think.

That said, Rubio, Kasich, Cruz and Bush are all in danger of repeating the fate of Lamar Alexander. Rubio and Cruz staffers I talked to were reluctant to predict that their candidate would finish any higher than fourth. A very small number of votes, maybe 7,591, could make the difference between entering South Carolina and the Southern Super Tuesday contests as a strong contender and entering them as an also-ran. On the Sunday before the Scottish independence referendum last September, the Queen was heard to advise that people "think very carefully" about how they vote. The candidates are not just uttering platitude when they say, as I heard Rubio and Cruz do today, to think very carefully about their vote.