Oct. 22 (Bloomberg) -- The Republican presidential candidates argued over who among them was a genuine conservative and competed to skewer Democratic frontrunner Hillary Clinton, while scratching the surface of how to hold down entitlement spending during a debate last night.

Rudy Giuliani, responding to a question about criticism leveled by former Senator Fred Thompson, cited tax cuts and a declining crime rate when he was New York's mayor as ``a pretty darn good conservative record.'' Thompson said his political leanings were set in college and went on to criticize Giuliani's stance on abortion rights and gun control.

Along with such personal exchanges, the forum in Orlando, Florida, delved into what to do about a looming fiscal crisis for the Social Security and Medicare programs, an issue largely absent from the six previous debates featuring all the front- runners.

Thompson said the government may have to curb the growth of future benefits to keep the programs solvent.

``We're bankrupting the next generation,'' said Thompson, 65. ``The indexing of benefits in the future, from wages to prices, is one way to'' avoid a future fight over ``a lot higher taxes or big benefit cuts.''

Giuliani, 63, backed adding private accounts for Social Security, a proposal that failed to win support when offered by President George W. Bush in 2005, and cutting the cost of health insurance so that more people can buy their own coverage.

Private Market

``If you start to establish a private market, you're going to be able to figure out how to solve these things within costs that are sustainable,'' he said.

Former Massachusetts Governor Mitt Romney, 60, said he ``was prepared to be entirely bold,'' in taking on the politically perilous issue of entitlement spending, ``but I'm not prepared to cut benefits for low-income Americans.''

He said he favored private accounts and would consider tying Social Security benefits to prices rather than wages for higher income Americans. Romney said ``effective leadership that brings people from both sides of the aisle together'' could solve the problem of escalating costs for Medicare and Medicaid, the government health insurance programs for the elderly and poor.

The debate, sponsored by Fox News and the Florida Republican Party, was the seventh such forum involving all the candidates and the first since Kansas Senator Sam Brownback dropped out of the race.

Criticizing Clinton

A recurring theme was the candidates using Clinton, who is leading in polls of Democratic voters, as a foil.

Giuliani, Thompson, Romney and Arizona Senator John McCain, the four leading Republican contenders, all trail her in head- to-head polls conducted by Fox. Prodded by debate moderator Chris Wallace, they rushed to offer their own criticism of the New York Senator.

``Hillary Clinton wants to run the largest enterprise in the world, the government of the United States,'' Romney said. ``She hasn't run a corner store. She hasn't run a state. She hasn't run a city. She has never run anything.''

Giuliani mocked Clinton for becoming a Yankees fan only when she moved to New York after growing up in the Chicago area, and McCain jabbed at Clinton for sponsoring $1 million in a spending bill for a Woodstock concert museum in New York.

McCain, who was a prisoner of war in North Vietnam from 1967 to 1973, drew laughter and a standing ovation when noted he wasn't at the 1969 Woodstock rock concert. ``I was tied up at the time,'' he said, adding, ``No one can be president of the United States that supports projects such as these.''

Taxes and Spending

Former Arkansas Governor Michael Huckabee, 52, and Thompson warned that a Clinton presidency would result in higher taxes. ``Taxes go up, health care becomes the domain of the government, spending goes out of control,'' Huckabee said.

At the start of the debate the front-runners were given a chance to take shots at their rivals and they took them.

After Romney and Giuliani were given a chance to respond to past remarks by Thompson questioning their commitment to Republican principles, Thompson said Giuliani ``sides with Hillary Clinton'' on abortion, gun control, and immigration.

Romney sparred with McCain, 71, who took a dig at the former governor as well as Giuliani, both of whom cited their past experience as qualification for the presidency.

``I wasn't a mayor for a short period of time. I wasn't a governor for a short period of time,'' McCain said. ``I didn't manage for profit, I led for patriotism.''

Thompson parried a question about whether he was ``lazy'' for taking a week off after the last debate and making some early stumbles.

``I was a father at the age of 17 and a husband at the age of 17, he said. ``I got started working in a factory. I borrowed and worked my way through.''

Thompson chronicled his rise from assistant U.S. attorney at age 28, to Watergate Committee counsel at age 30, and eventually to the U.S. Senate.

``If a man can do all that and be lazy, I recommend it to everybody,'' he said.

To contact the reporters on this story: Catherine Dodge in Washington, at Cdodge1@bloomberg.netNicholas Johnston in Washington at njohnston3@bloomberg.net.

Last Updated: October 22, 2007 00:11 EDT