Many were expecting Hillary Clinton to fall short of the challenge set by her husband, and fail to win both the Ohio and Texas primary elections. That she won these contests, as well as Rhode Island, has again focused the US media on the significance of superdelegates. These senators, representatives, governors and former presidents (including Bill), who are likely to decide the Democratic nomination, are being courted day and night by the Obama and Clinton campaigns. Nearly half remain uncommitted. The key question in their minds: which candidate has the support and policy positions to beat John McCain?

Obama’s electability, as reflected in head-to-head polls with McCain, had appeared robust. He has enjoyed a lead over the Republican nominee for the best part of a year but the latest poll of polls on realclearpolitics.com suggests that this advantage has been eroded. Clinton currently beats McCain, albeit by a tiny margin, but the Senator from Arizona had been beating her since the end of last year. How relevant is this to a superdelegate’s decision? The unreliability of polls was back in the news following the New Hampshire primary. Newspapers on both sides of the Atlantic were embarrassed when voters were greeted on the morning after Clinton’s first victory with pictures of a smiling Obama. And even George Gallup would not claim that opinion polls were of much use eight months before election day.

As in the UK, general elections in the US are not decided on a proportional basis. Each state is assigned delegates according to its size. In most states, the winning presidential candidate takes all these delegates to an electoral college, which decides the outcome. Few doubt that the Democrats will clean up on the eastern and western seaboards while the GOP will take the Deep South and Great Plains. The election will be determined in half a dozen swing states.

In the states where Kerry and Bush were within three percentage points of one another in 2004, Clinton has scored better among Democratic primary voters. She won Nevada, New Mexico, Ohio and New Hampshire and is widely tipped to win the Pennsylvania primary on April 22nd. Although it is unclear whether the vote will count for anything, she also took Florida, where the 2000 election was famously decided. By contrast Obama has only won the small Midwestern states of Iowa and Wisconsin. Of course, it is unclear how the crucial independents and disillusioned Republicans will vote in these states. But this group tends to be comprised of blue-collar workers, Hispanics and ‘soccer moms’, precisely the people who have formed Clinton’s coalition in the primaries so far.

So much for the electoral ‘math’. What about the issues? Obama is criticised for being light on policy but on the key topic of Iraq, he can justifiably claim that he opposed the war from the start. The difficulty for him is that John McCain is inextricably linked to the increasingly popular troop surge, which began over a year ago. In May 2007, only 32 per cent of Americans felt that the US army was making progress in Iraq. Since then, this number has increased steadily and 43 per cent are now positive about the forces’ impact. In the face of this upward trend, the Republican attack machine will go into overdrive to paint Obama as unpatriotic and too inexperienced to be commander-in-chief in a time of war. Recent coverage, indeed, has drawn attention to his decision not to wear the stars and stripes on his lapel.

Whatever Iraq’s importance to the election, the economy will be voters’ top concern. If the US is not yet in a recession, there’s a high chance that it will be by November. Both candidates have well-developed (not to say ‘techy’) economic policies. Clinton focuses on those who have lost their homes or jobs as a result of the downturn; Obama’s is higher-level with middle class tax cuts and benefit payments aimed at stimulating the economy. Voters are unlikely to examine the fine print and will instead look at the candidate’s credentials. Clinton will claim credit for her role as First Lady in creating America’s first fiscal surplus in 30 years but may find it harder to shake off her attachment to the North American Free Trade Agreement (NAFTA), which is proving unpopular. On this tricky issue, Obama may have blotted his copybook. One of his advisers told the Canadian government that the campaign was not really protectionist. Meanwhile in Ohio, Obama was telling voters the precise opposite. Whatever, Clinton’s lead on this key issue – as with healthcare – is wide.

Barack’s breed of ‘new’ politics (‘change we can believe in’) may well make all of this irrelevant. Indeed, a unifying candidate as inspiring and charismatic as Obama may be able to turn the tables on swing-state electoral analysis and win by a landslide. As the campaign planes zigzag across the United States until August’s conclusive Democratic National Convention in Denver, the two candidates will need to convince the undecided superdelegates of whether November’s election mantra should be ‘it’s the economy, stupid II’ or ‘hope springs eternal’.