On his path to winning the Democratic nomination, Barack Obama swore that he would change Washington by stamping out the influence of special interests who buy access and favours from the political establishment.

But there was little evidence that change was on the way in Denver. Despite the passage of ethics rules in Congress last year designed to curb the influence of lobbyists and other donors, the Democratic National Convention was funded almost entirely by corporations that pumped tens of millions of dollars into the event, using a loophole in campaign finance rules.