Leading article: A party that has strayed from the centre

America's Republican Party is currently dominated by its anti-Washington, anti-establishment, right wing. Alas, the right has yet to find a contender to its taste to take on President Barack Obama. That, in a nutshell, is why the potential Republican field remains so fluid, barely eight months before Iowa's caucuses kick off the process to select the party's nominee for 2012.

The candidates who have thus far declared are mostly establishment figures, led by the former state governors Mitt Romney and Tim Pawlenty, and the former House Speaker Newt Gingrich, while Jon Huntsman, governor of Utah before serving as Mr Obama's ambassador to China, may also join the race. For the right, however, all are essentially too moderate. That even the firebrand Mr Gingrich falls into this category is a measure of how far the party has strayed from the centre.

On the right, however, there is a vacuum, all the more obvious after Mike Huckabee, favourite of the Christian right and runner-up to John McCain for the 2008 nomination, announced last month he would not run. Thus the brief emergence of Donald Trump, before his candidacy collapsed under the weight of its own absurdity. The phenomenon also explains the surprisingly strong current showing of Herman Cain, pizza magnate and broadcaster, and the likely candidacies of former Senator Rick Santorum of Pennsylvania and the Tea Party favourite Michele Bachmann, Congresswoman from Minnesota.

It helps explain, too, the renewed fuss about Sarah Palin. The conventional wisdom has hitherto been that celebrity and a lucrative perch at Fox News held more appeal for the former Alaska governor than the brutal rigours of a presidential campaign. But the gap on the right may be too tempting to resist. And the vacuum is why party kingmakers are trying to persuade some who have said no to change their minds. Into this category fall Jeb Bush, the ex-president's brother and who, were his surname any other, would probably be favourite for the nomination, and New Jersey's combative governor, Chris Christie. But other names could surface. Like nature, politics abhors a vacuum.