Barack Obama is as skilled an orator as any politician in recent American history. With 75,000 adoring supporters cheering him along on Thursday night, his acceptance speech was always guaranteed to be a triumph. He could have read out the contents of the Denver metropolitan phone book and the crowd would have gone wild.

So what mattered about his performance was not the inevitably enthusiastic reaction from the loyal Democrats gathered in Denver’s Invesco Field, but how far it advanced his presidential campaign with a more doubtful public watching at home.

That was why his speech last night was very different from the sort of lyrical orations that have characterised his campaign so far. It was a much more traditional political speech, less lofty, more focused, less general talk of hope and more old-fashioned bashing of the opposition.

As a result, it risked undermining Senator Obama’s message so far that he stands for a different kind of politics, one able to transcend political divisions. While it addressed many of the problems that have weakened his campaign in recent weeks, it may in the end have done some new damage: perhaps Senator Obama is just another politician after all.

In this set-piece event he was trying to meet several objectives.

His first job was to introduce himself. As astonishing as it may sound, given that he has been running for president for 20 months, most Americans still don’t really know much about Senator Obama. The television audience – at an estimated 30 million or more – would be the largest that had ever seen him, and for the vast majority of them it was an opportunity to size up this man who has emerged onto the political scene so suddenly.

He spent much time talking about his background and his roots and emphasising of course that it was a true, if not a typical American story.

In the process he was trying to show empathy with ordinary Americans. His campaign has been criticised as being bloodless, aloof, too vague for a country which many people feel has lost its way. So on Thursday night he skillfully interwove his own life story with the struggles of ordinary Americans.

“I see in the faces of those young veterans who come back from Iraq and Afghanistan I see my grandfather, who signed up after Pearl Harbour, marched in Patton’s army,” he said.

He was also eager to attack John McCain, his Republican opponent, demonstrating that the Democratic candidate can go in for the kill if he needs to. He repeated the now familiar Republican claim that Sen McCain was campaigning for George Bush’s third term.

It’s a favourite Democratic talking point to note that as a senator, John McCain has voted with President Bush 90 per cent of the time.

“Senator McCain likes to talk about judgment but really, what does it say about your judgment when you think George Bush has been right ninety per cent of the times.”

Senator Obama also sought to allay fears he lacks the experience and stature necessary to be commander-in-chief. He insisted that his decision to oppose the Iraq war and his support for stronger US efforts in Afghanistan qualified him to be a better commander-in-chief than his opponent.

In all of these objectives, Senator Obama doubtless went some way towards reassuring voters.

But the biggest weakness of the speech may have been in its very attempt to address the criticism that his campaign lacks substance.

Senator Obama has been urged to talk less in general terms about change and more about what policies he would pursue in office.

On Thursday night he certainly delivered. He reeled off a long and at times numbing list of policies he would implement: tax reductions for working families, tax increases for companies that move operations overseas, support for clean-energy technologies, more money for education, a plan for health care coverage for all Americans,

The first problem with this list is not its newness but its familiarity. It is the same old promises politicians – especially those of the left – have made for decades. The second problem with this list is that if it were ever to be implemented it would cost a fortune in taxes. Senator Obama promises to avoid that with the usual politician’s claim that he will wipe out wasteful spending in government.

This is bogus and rather than restoring faith in politics as Senator Obama pledges, it only increases cynicism about politics.

The gap between Senator Obama’s promises and the reality of politics in America may be getting too wide.

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