Charlie Neibergall, File, Associated Press
FILE - In this Sept. 16, 2011 file photo, Republican presidential candidate, Texas Gov. Rick Perry speaks in Des Moines, Iowa. Wading into a tense foreign policy dispute, Republican presidential candidates Rick Perry and Mitt Romney on Tuesday criticized the Palestinian Authority's effort to seek a formal recognition of statehood by the U.N. General Assembly. The GOP rivals also used the jockeying at the U.S. to assail President Barack Obama's policy toward Israel.

MIAMI — Republican presidential candidate Mitt Romney is raising new questions in Florida about his rival Rick Perry's position on Social Security.

Romney said at a Miami town hall-style meeting that Perry's proposal to have states run the retirement system won't work. Romney asks what would happen if some states chose not to create a Social Security plan, and what would happen if people move from one state to another with a different system.

Romney, a former Massachusetts governor, says he wants to keep Social Security intact at the federal level and make changes to keep it financially healthy in the future.

The Miami event comes the day before the next big GOP presidential debate in Orlando. Social Security is likely to be a key issue at the debate.