Until a few weeks ago Barack Obama's economic platform was the most centrist of the three Democratic contenders remaining after John Edwards, the flag-bearer of the left, dropped out in late January.

Since Super Tuesday on February 5, that has changed. Scenting, perhaps, the chance of settling the nomination next week (when Ohio, Texas, Rhode Island and Vermont go to the polls), Mr Obama has indulged in a bidding war with Hillary Clinton to see who can rail most strongly against globalisation.