Newt Gingrich began to float gently upwards in mid-September. It was a slow, soft rise, like the movement of a day-old helium balloon or a parade float, but it was clear to most of us covering the race for the Republican presidential nominee that November would be National Newt Month.

Now Gingrich, the portly, dyspeptic former speaker of the House of Representatives, is enjoying his time atop the national and Iowa primary polls - time enough to remind voters why he started at the bottom: his complicated personal life; his lucrative decade as a Washington influence pedlar; his penchant for explosive, random suggestions, like replacing school janitors with platoons of children. "It is tragic what we do in the poorest neighbourhoods, entrapping children in, first of all, child [labour] laws, which are truly stupid," he told a surprised audience at Harvard University
this month.

The successive rise and fall of lesser Republican candidates has become a kind of sport and is certainly exhausting, for Republican voters and the political press alike. There was Michele Bachmann, a polished, brittle Tea Party fav­ourite, who soared in Iowa - until she came up against Rick Perry, the drawling governor of Texas, whose debate performances exposed a lack of preparation not just for the campaign, but for the presidency.

Topping the bill

Then came the little-known former pizza executive Herman Cain, whose outsider charm ran up against a proud ignorance of foreign policy and questions about his treatment of female subordinates. Underlying this flux are two core views about the invisible front-runner, the former Massachusetts governor Mitt Romney: that he can't win and that he can't lose.

The only reason to pay attention to the autumn antics is if you believe that Romney can't win. That argument goes something like this. Four years ago, when he lost the nomination to John McCain, Romney poured $10m into Iowa, whose homey caucuses in early January are the first Republican contest, giving the winner a surge of visibility and momentum as the campaign moves to larger states. That small fortune bought Romney about 25 per cent of the vote. This year, he has done nothing and still polls about 25 per cent of the vote. According to this theory, that 25 per cent of the electorate consists of all the Republicans who will vote for Romney, no matter what he does. The other 75 per cent are up for grabs - and thus, no matter how unprepared, unlikely, or plain strange the other candidates may be, one of them will be the nominee.

The political press has a certain vested interest in the possibility that one of Romney's hapless rivals must be the nominee. The cycle of rise and fall, strong first impressions and worn-out welcomes requires a basic belief in the other candidates' plausibility. The second and less entertaining theory is that the careful Romney is, at this point, the only plausible candidate for the nomination. Under that theory, the numbers tell a different story.

“The 25 per cent is more of a floor for Romney than a ceiling," the Republican pollster Ed Goeas, who worked for Bachmann until she ran out of money, said recently. There's quite a bit of evidence to back this up. Gallup's surveys, for instance, have found that while Romney doesn't command particularly "intense" support, he has one important asset - fewer Republicans report disliking him than any other candidate.

Nobody loves Romney; many like him. It's a picture that contradicts the broad feeling that conservative activists don't trust him. Lately those conservative activists have proved to be frustratingly difficult to find. A recent Los Angeles Times article on Tea Party disgruntlement failed to turn up a single Tea Partier who wouldn't cast his ballot for Romney next November. Romney's strategy, on the occasions when he emerges from his staff's careful "Mitt­ness Protection Programme", is to engage only President Obama.

On Tuesday 22 November, he seized on the latest example of Washington's dysfunction - the collapse of a "supercommittee" intended to reach a bipartisan compromise on budget cuts and tax increases - as an instance of Obama's failures. "It is another example of failed leadership," he said in New Hampshire. "He has not taken personal responsibility to get the supercommittee to find ways to balance the budget and cut spending. Instead he set a trap and said we are going to cut military spending by $600bn over the next ten years."

Yes, he (still) can

Obama is getting better at this, however. The failure of the supercommittee is the latest demonstration that his promise to bring harmony to Washington hasn't worked. But he met it with a sort of muscular promise. "My message to them is simple," he said of congressional leaders looking to wiggle out of planned cuts. "No. I will veto any effort to get rid of those automatic spending cuts to domestic and defence spending. There will be no easy-off ramps on this one."

Obama's tepid supporters cheered his new tone and some doubters believe he's finally growing into the office. One of them is the former senator George McGovern, the Democrats' hapless anti-war nominee in 1972. "I think he's going to be a good president. I have a feeling he's going to be stronger in the second term than he was in the first," McGovern told me recently. "I always thought that about President Kennedy - if he'd lived and was re-elected - he'd be stronger in the second term."

Obama's race will likely be as much against himself as against Romney, something the Republican also knows. Romney has honed his attack on the president - not as a wild-eyed socialist or a crypto-Muslim, as more radical elements of his party would have it, but as a nice man who is out of his depth. That is the portrait of the president that emerges from Ron Suskind's recent portrait of the Obama White House, Confidence Men.
A contest between Obama and Romney may well come down to whether the unloved Republican can convince voters that he's the only competent man in the race.

Ben Smith writes for politico.com and is the NS's American politics correspondent