ONE GETS a sense that, a bit like Bertie Ahern, Barack Obama enjoys playing the media, teasing with the admission that he has picked a vicepresidential running mate, but then, like the host of a TV talent show, tantalising further to guarantee maximum rapt attention. "Tonight's winner is . . ."
John Adams once described the VP job as "the most insignificant office that ever the invention of man contrived or his imagination conceived", but then found it a useful stepping stone to the big job. Indeed, some 14 vice-presidents have become president, nine of them inheriting the post for one reason or another (four because of assassination, two impeachment, one resignation), and five by election. And, most recently, Dick Cheney, has managed to fashion this "insignificant" post into the instrument by which, some would say, he effectively runs the country.
Obama's concern is more to do with the campaign than any eventual role in the White House. His choice needs to fill the gaps in his own curriculum vitae, whether in terms of perceptions of being weak on foreign policy experience, or in appealing to working class voters and states who supported Hillary Clinton but may be susceptible to John McCain.
His choice will help colour in the picture he must paint at next week's Democratic convention of Obama the man, still, strange as it may seem, a mystery to much of the American public. McCain has successfully labelled him both a remote intellectual and a lightweight celebrity, while many Americans appear determined to continue to believe he is a secret Muslim.
Obama's challenge, with the help of his VP, is to rebrand himself as a quintessential product of middle class America, sensitive to its preoccupations, not least its current cash worries. In swing states like Ohio and Pennsylvania, that will be particularly important. To that end he can only have been delighted by McCain's own-goal on Thursday in his startling inability to respond to a question about how many houses he owns - "I think I'll have my staff get back to you" (The answer is four or eight, depending on who you believe).
This should be strong Obama ground. A New York Times poll this week found that 40 per cent of voters want the campaign to focus primarily on the economy. On the issue, 65 per cent of those surveyed said they were confident that Obama would make the right decisions, with 54 per cent expressing confidence in McCain. When it came to foreign policy, however, the image was inverted: 66 per cent expressed confidence in McCain to make the right decisions, 55 per cent in Obama.
After the elaborately stage-managed party conventions - the Democrats from Monday in Denver and the Republicans, a week later in Minneapolis - the real race for the White House is officially on. Pollsters estimate that the conventions can give candidates as much as a 10-point surge in ratings. While Obama has seen his own star waning in recent days, with one poll this week suggesting a five-point lead for McCain, the road is still a long one and the battle has still to be won.