It was a comfortable and predictable win for Barack Obama in the last primary election before the Democratic campaign enters a kind of suspended animation for six weeks before the next contest, in Pennsylvania on April 22.

Mr Obama beat Hillary Clinton in Mississippi by about 60-40 per cent. The margin of victory was in the upper end of a range of predicted outcomes, but roughly of a scale that suggests the Democratic race is as wide open as it has been since the first votes were cast ten weeks ago.

If he had won in another blowout – say by 25 percentage points or more, as he did in some other southern states – it would have been a significant fillip for Mr Obama, suggesting perhaps once again that his persistent lead over Mrs Clinton in the race for the nomination might prove unassailable.

If the margin had been much narrower, below 10 percentage points, for example, the trickle of recent doubts about Mr Obama's sustainability might have turned into a flood. As it happened the solid Obama victory, in line with other states with similar demographic and political makeups, suggests a campaign battle that remains in delicate equipoise.

Mr Obama was supposed to win Mississippi. Half the voters were black, according to the exit polls, and they opted overwhelmingly for Mr Obama, nine to one. White voters chose Mrs Clinton by three to one. Race was so evidently the largest factor in the vote that it overwhelmed all other demographic and political considerations such as gender, income or attitudes towards the economy or the Iraq war.

In short, Mississippi leaves us absolutely no closer to knowing who will win the Democratic nomination. Mr Obama increased his sizeable lead among the pledged delegates to the party’s nominating convention. But his victory is unlikely to have shifted any more votes among the party’s undecided superdelegates, who will clearly actually determine the eventual winner.

The next six weeks will now feature two parallel but quite different electoral processes.

The first will be the Pennsylvania primary campaign. It is a big state, with 158 delegates at stake, and it is another must-win for Mrs Clinton on what should be demographically favourable turf for her.

The other process, perhaps of even greater significance, will be the Democratic party’s intensifying efforts to reach some resolution of its now notorious Florida-Michigan issue

These two states have already voted but had their elections nullified because they broke party rules on the timing of their primaries. Democratic grandees are currently scrambling to figure out whether to organise replays – perhaps some time in June after all other states have voted.

If this happens – and it seems increasingly likely – the two states would represent a kind of post-season playoff that could determine the ultimate winner.

They are both enormously important – between them they should account for about 10 per cent of the total Democratic nominating delegates. If there is a re-vote Mrs Clinton could very well win majorities in both states, (she won clearly in the first vote in Florida, with Mr Obama also on the ballot, though her victory in Michigan was meaningless since her opponent’s name did not appear). If that happened she would significantly narrow her deficit in terms of elected delegates and might even eliminate it in terms of the statistically meaningless but morally important overall popular vote.

Then the Democratic contest, already longer and closer than any other in recent historical memory, would start to get really interesting.

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