DENVER - Democrats are bristling with anticipation as they converge on the Pepsi Center for opening day of what is part one of this four part miniseries highlighting their nominee.

A quick scan of the papers and the polls shows there is much work to be done here in Denver. Obama must 1) work to unify Hillary Clinton supporters; 2) highlight his biography in a way that connects and resonates with middle America, 3) do something to assuage doubts about his lack of experience in foreign affairs and his ability to fill the role of Commander in Chief, and 4) drive home his core message that he represents change while John McCain would be a third term of George Bush.

That's a fairly long, not easily accomplished list. Obama will get a second crack at tasks 3 and 4 when he squares off with John McCain in the three presidential debates. But this may be his only - or at least his best - chance in what's left of the campaign to make serious headway on tasks 1 and 2.

So far, Obama hasn't done a particularly deft job of handling Clinton or her supporters. Indeed, he and his campaign have, at times, appeared to have gone out of their way to poke them in the eye. Over the next four days he has the opportunity to bring many of them back into the fold, and his success or failure in doing so could be critical to the final outcome of the election.

Task 2 is equally important. Obama must tell his story in a way that is convincing and compelling enough to make a lasting imprint on undecided voters who are tuning in to take the measure of the man. Because once the convention is over, the Republicans will go back to work on Obama's image and we will see even more references to his associations with Tony Rezko, William Ayers, and Jeremiah Wright.

The more Obama can firmly plant his feet by saying, "this is who I am, this is where I'm from, this is what I believe," the better he will be able to hold his ground during the maelstrom of the coming 10 weeks.

It's show time.