The news that Hillary Clinton is being backed by a group calling itself Puma almost has me warming to the woman. Puma stands for Party Unity My Ass. No beating about the Bush there. Or in this instance, bleating about the Obama.

The Democrats are in Denver this week for what is officially their convention but is more precisely a series of star appearances by their star act, Barack Obama. The star who would be President.

The Pepsi Center, which is the venue for the four day convention, isn’t quite the Bird’s Nest stadium. But don’t kid yourself that events here aren’t being as carefully choreographed by the politicos in Denver as they were by the politburo in Beijing.

Unfortunately for Democrat party bosses, however, la Hillary has not been so easy to hide away as the poor child in China whose appearance was similarly deemed likely to unsettle the audience.

What the organisers are worried about is that a convention floor show of strength from Hillary supporters would serve to point up the Puma in the room. The fact, in other words, that there is a deep division within the ranks.

Hillary can signal support for Obama. Bill can call Barack his homeboy. But there is no getting away from the reality that some in the grassroots who voted for Hillary and fervently believed — and believe — her to be the right candidate for the top job, just can’t move on.

This explains among other phenomena, the campaign group Democrats for McCain, which may or may not play a vital role in deciding the eventual outcome of the presidential race.

That it’s been such a fascinating race so far comes down not to the clash between the big two — Obama and McCain, the actual candidates.

But to the fight (and among their supporters it very definitely is a fight) between Obama and the Clintons. It has an oddly personal feel about it, this fight.

The Clintons, for all their onstage shows of support, continue to give the impression of a family robbed of what they believe was rightfully theirs. That second term in the White House.

To their supporters, keeping Obama out might let a Republican in. But it would, they seemingly believe, send the message: this is what you get for picking the lesser Democratic candidate. And there are thousands who undoubtedly believe that Obama is the lesser candidate compared to Mrs C.

Hell hath no fury like the supporters of a woman scorned.

And these are the people who have the power to decide who is the next President of the US.

That McCain is a bit of a maverick, a not so run-of-the-mill Republican, makes it easier for them to consider the cross-over.

Obama’s choice for Vice President, Joe Biden, may be a smart move in terms of potentially attracting some of the blue collar vote that the former so obviously lacks. (Although from this side of the Atlantic choosing as your running mate a man who plagiarises Neil Kinnock, God help us, does not seem quite so inspired.)

But this smart move is unlikely to go down well with those who believe a smarter move would have been Hillary Clinton. In many ways the ferocity of the campaign between the two Democrat candidates ensured that they would never make a Dream Team ticket.

But that won’t stop the Hillary loyalists thinking of what might have been. And feeling vengeful on account of it.

Over 20% of Hillary voters already say they are prepared to vote for McCain. But telling almost another third say they haven’t made their minds up.

As he sharpens his claws for the final battle in this compelling presidential contest, it’s not just the Republican top cat Obama now has to tackle.

But the Puma in his own backyard.