The notion that Mr Romney could portray himself as a champion of the struggling middle-class might have seemed fanciful a few months ago, but it is now a central theme of the Republicans’ campaign.

The Democrats’ mistakes add weight to the biggest factor working in Mr Romney’s favour, that the economy and jobs growth are stalling, a trend that could be fatal for the president’s re-election hopes. …

Mr Romney’s message about the stagnant economy falls on fertile ground in central Florida, where the mortgage market was among the worst hit by the financial crisis and is still falling in parts of the state.