Obama refocuses | Video: watch Obama's speech | Video: watch Clinton speech | Behind the scenes | Clinton ignored

Barack Obama gave yet another primary night victory speech on Tuesday as he has, it seems, every Tuesday for the last five months.

But this time the smoothly oiled Obama campaign had made a very conscious effort to make it look and sound a little more final than all of his previous efforts.

He spoke not in Oregon, the state whose primary he actually won on Tuesday, but in Iowa, the symbolic site of his first victory back in the first week of January, the state that propelled his candidacy from idealistic impossibility to plausible probability.

Iowa is not only a good place to begin and end a primary campaign. It is a pretty promising place to launch a general election campaign. It is a swing state. George Bush won there by just 10,000 votes out of 1.5m in 2004 and it is high up there on the list of Democratic targets for 2008.

And the speech itself, full of the usual soaring rhetoric by the young Illinois senator, sought at least in oratorical terms to draw a line under his long primary struggle with Hillary Clinton. He was especially gracious to his nearly defeated opponent.

“Senator Clinton has shattered myths and broken barriers and changed the America in which my daughters and your daughters will come of age, and for that we are grateful to her,” Mr Obama said.

But he insisted that, since yesterday’s primaries had now given him a majority of the elected delegates up for grabs in the Democratic race, the battle was all but over.

“We have returned to Iowa with a majority of delegates elected by the American people, and you have put us within reach of the Democratic nomination for president of the United States in America,” he said.

And yet, there was still something missing. A concession speech by his opponent.

Mrs Clinton, having earlier won the other state primary on Tuesday in Kentucky, was having none of it. She insisted, in the face of almost universal incredulity among the pundits, that she could still come out on top when the race ends.

“I'm going to keep making our case until we have a nominee, whoever she may be,” she said to a delighted crowd in Louisville.

She won Kentucky by a margin similar to the one she secured last week in West Virginia, propelled by the same large group of white working-class voters who seem to show no enthusiasm for Sen Obama.

But even with that impressive win, and even though Sen Obama couldn’t quite claim the victory he had been hoping for last night, Mrs Clinton’s arithmetical mountain is still hopelessly insurmountable.

Sen Obama’s claim that he had now won a majority of pledged delegates was a useful piece of symbolism for his argument that the Democrats’ pivotal super-delegates must simply ratify the votes of elected delegates, though it was not truly dispositive. He still needs to get those extra super-delegates to clinch the nomination. But now he is well within sight of the finishing line. He needs little more than a quarter of the small number of delegates that have still to declare themselves to grasp the prize. All the signs are that he will get those votes in early June, after the last states have voted and when the remaining super-delegates will make their selection.

Does Sen Clinton have any hope? Not really. She has two aims. She must narrow the gap in delegates to such a small number that it somehow looks like a near-tie. To achieve this her main hope is to somehow persuade Democratic officials that they should agree to give her a large number of delegates out of the currently disallowed states of Michigan and Florida.

Then her second aim is to amass enough of a popular vote win in the remaining three primary contests – most notably Puerto Rico, the largest of them - so that she can claim at least on some measures, a narrow popular vote win over Sen Obama.

These two tasks both look beyond her reach, and nothing that happened on Tuesday alters the general impression that Sen Clinton will be forced to concede defeat eventually – probably in the first or second week of June.

After that the Democratic party will have to hope that Sen Clinton is wrong when she warns that, if the recent primary contests are any guide, Sen Obama will have real problems in a general election against Republican Senator John McCain with white working-class voters.

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