One month after formally declaring his candidacy for president, former Sen. Fred Thompson of Tennessee finally climbed in the ring Tuesday with eight other Republican contenders to trade some spirited campaign punches.

And while Thompson literally stood front and center absorbing some early jabs about his late entry into the race for the White House, he also showed he can be a deft counter-puncher.

"Is this our sixth debate, I think — something like that?" asked former Massachusetts Gov. Mitt Romney. "And this has a lot — this is a lot like 'Law & Order.' … It has a huge cast, the series seems to go on forever and Fred Thompson shows up at the end," he joked.

Thompson, however, didn't miss a beat, deadpanning, "And to think I thought I was going to be the best actor on the stage."

But while Thompson's name appeared to top the fight card at the University of Michigan-Dearborn, the real slugfest came later during a spirited — and sometimes heated — exchange between Romney and former New York City Mayor Rudy Giuliani.

The two Republican frontrunners continued a battle started last week over who will claim the title of true fiscal conservative, this time going toe-to-toe on taxes and spending.

Romney, whose father once governed Michigan, initially turned the argument on the state's Democratic Gov. Jennifer Granholm, who he said raised taxes and is continuing to keep the state in a recession. He drew laughter when he said he was afraid she "was going to put a tax on this debate."

But the debate turned feisty when Giuliani, who is leading in national polls, claimed he lowered taxes 23 times, cut $9 billion from the budget and reduced per capita spending by 7 percent while serving two terms as New York City mayor. He argued that while Romney was governor of Massachusetts per capita spending went up 8 percent.

Romney, who made millions as a venture capitalist, countered that he cut taxes as well, and quoted the Club for Growth finding that spending went up 2.2 percent annually under Romney, but 2.8 percent under Giuliani.

Romney added that the best tool to keep spending down is with a line-item veto, a device that tax-cut proponents say would help reduce spending, and Romney said he used 847 times.

Giuliani noted that the U.S. Supreme Court has said that the line-item veto is unconstitutional for the federal government, and he prosecuted the case against giving that authority to President Bill Clinton.

"You can bang your head up against the stone wall all you want. I am in favor of a line item veto, expect you have to do it legally. And as the mayor of New York, if I had let President Clinton take $250 million away from the people of my city illegally and unconstitutionally, I wouldn't have been much of a mayor," he said. "So I took President Clinton to court and I beat him. And I don't think it's a bad idea to have a Republican presidential candidate who actually has beat President Clinton at something."

Giuliani also turned his attention toward the Clinton clan when he suggested that a robust America would be ensured through a proper fix to the health care system, not the one Democratic presidential front-runner Hillary Clinton has proposed.

"America — the possibilities for America in this global economy are endless, if we don't put a lid on ourselves," Giuliani said. "Hillary Clinton, the governor mentioned, wants to put a lid on us. She wants to put a lid on our growth. We want to give people freedom.

"I'll give you an example. Hillary, the other day — remember the Hillary bond program? She's going to give out — she's going to give $5,000 to every child born in America, with her picture on it," he continued. "I challenged her on it. I challenged her. She has backed off that. She has a new one today. This one is, she's going to give out $1,000 to everybody, to set up a 401(k). The problem is, this one costs $5 billion more than the last one."

Thompson, meanwhile, said he had no regrets about entering the contest just one month ago, at least six months after the other candidates on the stage.

"I don't think I waited too long. It seems about right to me," Thompson said. "I've enjoyed watching these fellas. I've got to admit, it was getting a little boring without me, but I'm glad to be here now."

Speaking about the overall economy, Thompson — who was first to answer a question — said he sees no evidence recession is coming, though measures need to be taken to ensure long-term economic prosperity.

"We're enjoying 22 quarters of successive economic growth that started 2001 and then further in 2003 with the tax cuts that we put in place," he said. "But we are spending money we do not have. We are on a mandatory spending lockdown that is pushing us in a direction that is unsustainable. We're spending the money of future generations, and those yet to be born. That has to do with our mandatory spending problem."

But winning over Republican voters in Michigan could hinge on being the most aggressive anti-tax and anti-spending candidate, and the GOP contenders were quick to support, or as Colorado Rep. Tom Tancredo said, "at least pay lip service to" efforts to control spending.

As for ensuring the strength of America's future, the candidates sounded several positive notes.

"Right now, [the U.S. is] less than 5 percent of the world's population, yet 20 percent of the world's economy, a third of the world's military spending," Sen. Sam Brownback, of Kansas, said. "Forty percent of our research and development budget around the world is in this country. I mean, this place rocks."

Brownback said he supports a flat tax, and suggested private Social Security accounts to help keep America strong. Brownback and Tancredo both pledged not to raise taxes if elected president.

Other candidates, including Mike Huckabee and Rep. Duncan Hunter, of California, both advocated a fair tax system that would remove taxes on productivity and exports, and Huckabee claims, would lift up lower income Americans.

Several candidates also argued for free trade, but Hunter said China is cheating on trade, leading to a loss of jobs in the U.S. Rep. Ron Paul, of Texas, complained that the U.S.'s biggest export is dollars, which is leading to a debt of $2.7 trillion owned by foreigners.

"As long as we live beyond our means we are destined to live beneath our means. And we have lived beyond our means because we are financing a foreign policy that is so extravagant and beyond what we can control, as well as the spending here at home. And we're depending on the creation of money out of thin air, which is nothing more than debasement of the currency," Paul said. "It's counterfeit."

As is often the case, several members invoked Reagan's name. Sen. John McCain, of Arizona, said the former president would be "spinning in his grave" if he could hear the Republican candidates bashing free trade. He then said he would open the global market to U.S. agricultural exports in exchange for importing sugar cane-based ethanol.

"And, by the way, I have a glass of ethanol every morning before breakfast," he said. "But I still don't support the subsidies. And I don't think we need them."

Huckabee, on the other hand, stressed the need to become energy independent, even if it means offering incentives to get companies to develop ethanol and other biofuels.

"We can't wait until another generation," he said. "Instead of running it like NASCAR, we've been running it like taking the family station wagon in for letting Goober and Gomer take a look at it when they get time, under the shade tree. So it's critical that for our own interest, economically and from a point of national security, that we become energy independent and commit to doing it within a decade."

Thompson then offered to explain to the northern audience who the Goober and Gomer characters were from "The Andy Griffith Show."

Tancredo and McCain both blamed out-of-control budgets in Washington, D.C., on excessive spending on entitlements like Social Security. Tancredo added that illegal immigration is costing the government $20,000 for every $10,000 that an illegal contributes to the economy, and blamed illegal immigration for other ills in the U.S.

"The creative conflict that occurs between unions and management is usually a good thing. When unions, I think, get off track is when they start to influence public policy, especially with regard to, need I say it, illegal immigration, allowing illegal immigration into the country because they want to fill up their ranks," Tancredo said.

On a separate topic, McCain praised President Bush for vetoing the State Children's Health Insurance Program bill, and he urged him to reject a multibillion-dollar public works measure as well.

"We've got to get wasteful spending under control," he said.

The candidates also expressed their support for the war in Iraq, with Paul, the sole opponent, winning applause for saying the U.S. is bogged down under phony pretenses.

While criticizing Bush for not sending in enough troops initially, Thompson said the war in Iraq is one against Islamic fascists who want to bring down Western civilization, and it must be fought.

"Sometimes it's strange to me to think that the average 20-year-old serving us in Iraq knows more about what it takes for our national security than the average 20-year veteran on Capitol Hill," he said.

McCain suggested establishing an OSS like that in World War II to find terror leader Usama bin Laden. He then returned to the question of support for the GOP nominee, countering poll numbers that suggest he may not win the vote.

"By the way, supporting the nominated party, of course, I would support me," he said. "The president of France is a pro-American; I'm glad he's doing what he's doing and it shows that if you live long enough, anything is possible."

The latest Republican primary poll in Michigan conducted by Insider Advantage has Thompson in fourth place among 1,190 voters, behind Giuliani with 19 percent, Romney with 16 percent and McCain with 14 percent.