From a Republican point of view, the American presidency is there for the taking. In Iowa, which Barack Obama won easily in 2008 with 54% of the vote, the president's approval ratings are languishing in the mid-40s. So many of the people who flocked to the inspiring candidate then are disillusioned with his performance as president today as the economy stutters and unemployment remains high. He is vulnerable on the right for healthcare reform, and on the left over his inability to stand up to Congress. What more could an aspiring Republican candidate want? Very little, but first the party has to find one.

They have made extraordinarily heavy weather of the task. In as many months, they have gone through six frontrunners. Michele Bachmann, the self-styled Margaret Thatcher of the campaign trail, whose cable television presence developed a national following among the Tea Party base, might well come last in Iowa tomorrow. The chairman of her campaign in the state last week defected to a rival candidate's side. For its ineptitude, Bachmann's campaign can only be matched by Rick Perry's. He has shed his pair of brown ostrich cowboy boots, with the words "liberty" and "freedom" emblazoned on them, but has never been able to recover from his own mistakes, like that "oops" moment, when he could not remember the name of one of the three government departments he wanted to close. Herman Cain's bid, which had more exposure on Fox News than any other, is no more. Newt Gingrich's fortunes have waned and waxed and waned again, battered by $2.5m of television ads. They hammered the former speaker of the house for a consulting deal with Freddie Mac.

Three have a hope of winning Iowa. The cash-strapped former Pennsylvania senator Rick Santorum has momentum and the evangelical Christian vote (just as Mike Huckabee had in 2008). He is reaping the reward for having spent more time on the ground than any other candidate. Ron Paul has the organisation and funding to go all the way to the convention in August. A win for either in Iowa would be problematic for the establishment Republicans. A Ron Paul win would allow the Democrats to portray the GOP as extremist – in his book Freedom Under Siege he claimed that Aids sufferers "victimised" others by forcing them to pay for their care – and a Santorum win could not be repeated in New Hampshire, South Carolina or Florida, the next three states where Republican primaries are held.

That leaves monotonous Mitt Romney, who has kept himself disciplined, on time and on message – avoiding any mention of God, guns, gays or Ronald Reagan – but can only do this by being robotic. Mr Romney consistently fails to grab the imagination. If poll ratings were a fuel tank, his would be never be more than one-quarter full. But Mr Romney labours under another handicap. He is also known as a moderate, a lethal tag for any modern conservative to bear, even though his statements on Iran would make Nato's hair stand on end.

Put it all together and the field is a fair reflection of a party so divided, so dominated by ideological demons, so beholden to the dangerous concept of fundamental truth, that they fear each other more than they do the Democrats. A party that produced in the past lead actors has been reduced to the role of an agency that provides reliable walk-on parts. This should be good news for the Democrats – but they, too, will go into the November elections on the defensive, battling to save a presidency, rather than making a positive case for a second term. Staying in power to safeguard the limited achievements of healthcare reform and benefits will be regarded as victory enough. But no final battle will have been won. The dysfunctions of a system which paralysed the radical hopes of one presidency are on course to finish the job in the sequel.