JOHNSTON, Iowa (CNN) -- The leading Republican presidential candidates threw a few jabs but mostly struck an optimistic tone Wednesday in their last debate before January's Iowa caucuses.
The nine Republican presidential candidates mostly avoided attacking each other during Wednesday's debate.
Former governors Mike Huckabee and Mitt Romney didn't bring their recent fights over immigration to the stage.
"I kind of anticipated that there would be blood on the floor, most of it mine," Huckabee, the former Arkansas governor who has risen to the top of the polls in recent weeks, said after the debate.
The organizers, The Des Moines Register and Iowa Public Television, took the hot-button issue of immigration off the table from the start to push the focus of the face-off toward the economy, health care and education.
With less than a month before the January 3 caucuses, the first contest of 2008, most of the front-runners appeared unwilling to challenge each other directly, leaving the fireworks to the second-tier contenders -- including conservative commentator Alan Keyes, who criticized debate moderator Carolyn Washburn of the Des Moines Register for short-changing him on time in his first appearance with the field's leaders.
It was a substantive debate on a number of issues that normally don't see the spotlight at such debates, such as the national debt, free trade, and education.
The debate was to focus on "issues Iowans say they still want to know more about," Washburn said in her opening remarks. "We won't talk a lot about issues like Iraq or immigration. They're important issues, no doubt, but Iowans say they know where the candidates are coming from on those."
While Iowa voters may now have a slightly better understanding of where the Republican presidential candidates stand on those issues, the debate will probably not make much of a difference on where the candidates stand in the Iowa presidential race.
During the hour-and-a-half session, former Tennessee Sen. Fred Thompson said he would level with Americans about the costs of Social Security and push for changes "that won't hurt anybody badly, but will save it for the next generation."
Arizona Sen. John McCain, showing off the maverick streak underlying his reputation, backed not only free trade but also an end to farm and ethanol subsidies -- popular programs in the Corn Belt.
"I don't believe anybody can stand here and say that they're a fiscal conservative and yet support subsidies and destroy our ability to compete in the world," he said.
Giuliani pledged to cut the corporate income tax rate for highest-revenue companies from 35 percent to 25 percent, which he said would boost the economy and provide "a major boost in revenues for the government." Huckabee said he would shift the focus of U.S. health care toward preventive care, which he said would bring costs down -- a step he said would "kill the snake rather than just treat the snake bites."
And Romney, who has led polls in Iowa through most of the past year, said he supports tax relief for the middle class, whom he said are "under a lot of pressure" from rising fuel and health-care costs.
"I don't stay awake at night worrying about the taxes rich people are paying, to tell you the truth," said the former Massachusetts governor, an automotive heir who made a fortune as an investment banker before entering politics.
That prompted a flash of wit from Thompson, who replied, "My goal is to get into the Mitt Romney situation where I don't have to worry about taxes anymore." When Romney responded that he was "trying to get into your situation," the former star of the television drama "Law and Order" shot back, "You're getting to be a pretty good actor."
Thompson was also the most vocal of the candidates who balked at a show of hands as to which candidates believe global warming is real and the result of human activity. He also refused to give a yes-or-no answer on the issue, prompting Washburn to skip him on the question.
Among the second-tier candidates, Rep. Duncan Hunter of California, the former chairman of the House Armed Services Committee, warned of the military and economic threat of a rising China and pledged to bring high-paying manufacturing jobs back to the United States if elected.
Rep. Tom Tancredo of Colorado, who has made illegal immigration the centerpiece of his campaign, accused Romney of switching positions on the issue. And anti-war Rep. Ron Paul of Texas said the United States could shore up its finances by withdrawing American troops from the hundreds of bases it now has overseas.
"We maintain an empire which we can't afford," he said.
Meanwhile, Keyes -- who is making his third bid for the GOP presidential nomination -- said the biggest problem facing American education is that "we allowed the judges to drive God out of our schools."
"They don't want to talk about this, except when they are squabbling about their own personal faith and forgetting that we have a national creed," he said of the other candidates. "The national creed needs to be taught to our children. Whether they are scientists or businessmen or lawyers, they will stand on the solid ground of a moral education that gives them the discipline they need to serve the right."
Keyes last appeared in a PBS-sponsored debate at Baltimore's historically black Morgan State University, an event the party's front-runners skipped. He met the criteria for Wednesday's debate, which requires a 1 percent showing in an October poll by the Register and having a campaign office and at least one staffer hired by October 1.
Two Democratic presidential hopefuls -- Rep. Dennis Kucinich and former Sen. Mike Gravel -- failed to meet those standards for that party's Iowa debate, slated for Thursday at 2 p.m. E-mail to a friend
CNN's Paul Steinhauser contributed to this report.