HANOVER, N.H. (AP) — Former Massachusetts Gov. Mitt Romney is defending the 2008 bailout of Wall Street banks, saying it was essential to preserving the nation's currency and financial system from collapse.Romney said the U.S. could have had a "complete meltdown of our entire financial system." He said "action had to be taken. Was it perfect? No."Asked if he would support another bailout, Romney said that if he thought the entire financial system would collapse, "you take action to keep that from happening."But he said he opposed bailing out individual companies, citing his opposition to the bailout of automaker General Motors.Romney made his statement during the Bloomberg-Washington Post presidential debate at Dartmouth University.