Republican candidates in heated exchange

Republican presidential rivals Rick Perry and Mitt Romney tangled over their records on creating jobs in a campaign debate that marked a contentious new turn in the race to pick a challenger to President Barack Obama next year.

The debate was the first of three in as many weeks, at a time when the economy is struggling, unemployment is seemingly stuck at 9.1% and Mr Obama's popularity is sinking in the polls - all making the president seem more vulnerable than he appeared only a few months ago.