The 2012 United States election begins on Thursday when Iowa becomes the first state to hold contests to decide who will be the Democratic and Republican presidential candidates in November.
Although Barack Obama will be renominated as the Democratic contender, the Republican race's outcome is uncertain.
In November and early December, Newt Gingrich surged in national opinion surveys of Republican identifiers. But can the controversial ex-leader of the House of Representatives really become the Republican nominee?
Gingrich does have a plausible outside chance. The past few decades of US political history indicate the victor in presidential nomination contests usually leads national polls of party identifiers on the eve of the Iowa ballot, and raises more campaign finance than any other candidate in the 12 months before election year.
From 1980 to 2000, the eventual nominee in eight of the 10 Democratic and Republican nomination races was the early front-runner by both of these measures.
In the two exceptions, 1980 and 1988, an eventual presidential nominee led the field on one of the measures. In the 1980 Republican race, Ronald Reagan led national polls of party identifiers, although John Connally raised most funds. In the 1988 Democratic contest, Michael Dukakis raised most funds but trailed Gary Hart in national polls.
This year's Republican race resembles those contests. As Iowa approaches, no candidate is a clear leader on both measures: Romney raised the most money in 2011, while Gingrich led some of the national polls.
So who is best placed to win between Romney and Gingrich? At this stage it's most likely Romney will prevail, possibly with ease. His campaign has superior financing and better national organisation of support, evidenced by his recent success in securing the 10,000 signatures needed to get on the Republican nomination ballot in Virginia, and Gingrich's failure to do so.
Nonetheless, Gingrich still has an outside chance, especially if he, unexpectedly, wins big in Iowa and this gives him momentum in a critical mass of subsequent state nomination contests across the country.
Other candidates should not be discounted. Neither Obama (the Democratic candidate in 2008), John McCain (the 2008 Republican candidate) nor John Kerry (the Democratic candidate in 2004) was an early front-runner on either polling or fundraising before Iowa. Obama, for instance, was in Hillary Clinton's shadow for much of the year before the 2008 election season began.
Whether Romney, Gingrich or another candidate wins the nomination, a key factor that will influence Republican prospects against Obama will be whether, and how quickly, the party unites around the nominee. A model for Republicans is Bush in 2000 who emerged strongly from a wide field of contenders before going on to, controversially, defeat the Democrats' Al Gore in November.
However, it may be harder for Gingrich or Romney to unify the party this year. Romney hit a relatively low ceiling of support last year of around 25 to 30 per cent of party identifiers. This is largely because his moderate conservative views (which make him more electable than Gingrich against Obama) have alienated many right-wing Republicans, including those with Tea Party sympathies.
By contrast, Gingrich is generally perceived as a maverick by the Republican establishment which doubts his electability against Obama.
Moreover, Gingrich's support from right-wing Republicans could also prove fickle inasmuch as they have concerns about his perceived ethical wrongdoing, but nonetheless appear to view him - for now at least - as the most credible "stop-Romney" candidate.
Whoever ultimately wins the nomination, most Republican operatives are particularly keen to avoid a bruising, introspective and drawn-out contest which exposes significant intra-party division to the national electorate. The last time such a scenario unfolded for Republicans, in 1992, the chief beneficiary was Democrat Bill Clinton, who won a relatively comfortable victory.
While the circumstances of 2012 are different from 1992, another divisive Republican contest would almost certainly provide a much needed boost for the Obama campaign's fortunes.
With the President's job approval ratings remaining at or below 45 per cent, he remains potentially highly vulnerable to defeat.
Indeed, Obama's re-election prospects may now rest to a very significant degree on a factor that is largely out of his hands. That is, whether the US economy can stage a much more vigorous recovery in 2012 when other areas of the world appear to be heading back into recession.
Andrew Hammond is an associate partner at ReputationInc. He was formerly US editor at Oxford Analytica, and a special adviser in the Government of British Prime Minister Tony Blair.