The real problem with this is not the cod-religious congratulation of being the chosen ones, but a quieter, more insidious message: that the campaign itself is the change he talks about.

In this way, the Obama campaign is styling itself as a sign of change, rather than an argument for it. As he said in South Carolina: "We are showing America what change looks like." In that linguistic and conceptual manoeuvre, the goal of accomplishing the specific changes Americans urgently need - in health care, the economy, education - is relegated to the background. You're not so hungry for reform when you've already feasted at the table of self-congratulation.

While the first celebrity song had the energising feel of a rallying cry, this second video features Hollywood types Jessica Biel and Ryan Philippe anointing themselves as "the ones", encouraging their fans to join them, to become part of the "movement", to "change the world"....

While Clinton's campaign sets out her credentials and her plans for what she describes as "the most difficult job in the world", Obama's is a campaign deliberately operating on a symbolic level. Clinton is asking Americans to hire her to do a job; Obama is asking them to believe in him.

Accordingly, they offer two different models for the Presidency: put it in terms of the much discussed "day one", the Obama model is about the inauguration speech, and Clinton's is focused on the moment she gets back from the Capitol, sits down at that desk, and starts work.

This second Will.I.Am video is a perfect example of what has swept Obama to this point, but also of what has been his undoing in Texas and Ohio this week and what will be difficult for him the races to come.

For what remains to be seen is whether the American people continue to enjoy watching a bunch of celebrities congratulating themselves on being "the ones."