You can't beat somebody with nobody. That hoary truism applies equally to war, sport and politics. And rarely has it been more relevant than apropos next year's fast-approaching US presidential contest, pitting Barack Obama against – well, whom?

In normal election cycles, the moment the midterm results are in, the presidential campaign begins. But not this time. The Republican triumph in 2010 is now more than six months past; you would have imagined that, with the White House seemingly winnable, the party's biggest names would have been jostling to become the 2012 nominee. If anything, though, the opposite has been true. The line-up is unclear, the war is still phoney, and many activists are openly unhappy with the choice thus far on offer.

But that must change soon. Presidential campaigns are like icebergs: a candidate's speeches and television appearances are but the visible part of a mighty enterprise of fundraising, networking and grassroots organising that usually has long been under way. So here is a snapshot of the race, broken down into four categories: who's out, who might be in, who's certain to be in, and the "if onlys".

First, the "outs". A couple of weeks ago Haley Barbour, the canny governor of Mississippi, surprised even close friends by deciding he lacked the "fire in the belly" to run. Then Donald Trump bowed out, having reaped a publicity bonanza with which to launch a new season of Celebrity Apprentice. Then, and most significantly, Mike Huckabee – owner of his own show on Fox News, runner-up to John McCain in 2008, and who certainly would have done well next year – said he wouldn't run, depriving the Republicans' powerful socially conservative wing of its most plausible standard bearer.

Next comes a foursome yet to make up their minds. Mitch Daniels, once White House budget director and now the competent but rather dull governor of Indiana, says he will decide very soon. Old-school Republicans would love a Daniels candidacy; indeed, in these deficit-troubled times, boring may be chic. Alas, his wife is not keen on the idea; more than likely, Daniels will not run.

On the other hand, John Huntsman, fluent and telegenic, a former Utah governor and, until last month, Obama's ambassador to China, probably will – at least if last week's five-day trip to New Hampshire, home of the first primary, is any pointer.

The problem is that three out of four Republican voters have never heard of Huntsman, who in any case may be too moderate to survive the primaries. Sarah Palin, by contrast, clearly has no problem on either score, and Huckabee's departure provides her with an obvious opening. Like him though, she may decide that lucrative celebrity on Fox is preferable to the 24/7 ordeal of a presidential race – one, moreover, that she has no chance of winning. In which case the conservative mantle may fall upon Michele Bachmann, the Tea Party's loudest champion in Congress.

Then there is the group who, to all intents and purposes, are in the race already. If anyone is a front-runner it is Mitt Romney, who has been plotting a 2012 campaign from the moment he lost in the primaries last time around to McCain. Romney is experienced, and is winning hands down the vital "money primary" of fundraising. But he creates little excitement, and carries the albatross of Massachusetts healthcare reform that was his greatest achievement as governor of that state, but which is virtually indistinguishable from the "Obamacare" reviled by all right-wing Republicans. Each attempt to explain the contradiction only compounds his reputation as a flip-flopper.

Unlike Romney, who technically is still at the campaign exploratory committee stage, Tim Pawlenty will make his candidacy official today. But despite two solid terms as governor of Minnesota, Pawlenty stirs few souls. If he wins the nomination, they say, it will be as last man standing, after every rival has stumbled or self-destructed.

Which, of course, is cue for the hyperbolic and intemperate Newt Gingrich, who has surprised no one by committing a mega-gaffe barely a fortnight after throwing his hat into the ring. His criticism of his own party's official proposal for Medicare reform as "right-wing social engineering" prompted one gleeful Democrat senator to declare: "For the first time ever, I agree with Newt Gingrich." The thrice-married former Speaker is also having to explain why he once ran a $250,000 debt at the jewellers Tiffany and Co.

A few smaller fish must be noted, too: Rick Santorum, a former senator who blames America's economic woes on abortion; the libertarian Ron Paul, who calls for the abolition of the Federal Reserve, a return to the gold standard and the legalisation of heroin; and the pizza-chain owner and talk-show host Herman Cain.

In short, every "in" has a drawback. And so to the "if onlys". Foremost among them is Jeb Bush, brother of the last president and former governor of Florida, who Republican strategists believe would be the party's strongest candidate in 2012. Unfortunately, Bush wants to keep his powder dry until 2016. But, these same strategists fondly wonder, might he yet be persuaded to jump in this time, if all else fails? Much the same goes for Chris Christie, the blunt-talking governor of New Jersey, even though he swears to everyone who will listen that he is sitting out 2012.

In fact, the biggest peril facing Republicans is a repeat of 1972 when George McGovern was buried in one of the greatest presidential landslides ever, inflicted by Richard Nixon no less. Back then, liberals had dragged the Democrats far to the left of what the country would accept. The Tea Party poses a comparable threat from the right to today's Republicans.

But Obama is not invincible. The president basks in the glory of having hunted down Osama bin Laden. But his fate in 2012 will be settled by the economy. A new downturn, a new jump in unemployment – and a mainstream Republican (Romney, Pawlenty, Huntsman, even Jeb Bush?) who talks credibly about the economy would surely have a chance. First though, you need a somebody.