Washington  - Democrat Barack Obama and Republican John McCain began their second presidential debate Tuesday night in a discussion on the economy against the backdrop of a widening global credit and economic crisis.

In the only presidential debate scheduled in the so-called town hall meeting format, the two candidates quickly heard questions from a group of 80 undecided voters about the financial crisis in the United States and the 700-billion-dollar rescue package approved last week in Congress.

Global stock markets have continued to plummet this week as banks in Europe stumble into crisis, with governments there crafting their own bailout plans. (dpa)