Republican presidential rivals called Wednesday for deep cuts in federal spending, and said the reductions need not require painful sacrifice by the millions of Americans who receive government services.

"The sacrifice we need from the American people is saying, 'Let the programs go that don't work. Don't lobby for them forever," said former Massachusetts Gov. Mitt Romney, one of nine GOP presidential hopefuls sharing an Iowa debate stage little more than three weeks before the state's caucuses provide the first test of the campaign.

Former New York Mayor Rudy Giuliani called for across-the-board cuts of up to 15 percent, including reduced federal spending on health care. "Rather than relying on a nanny government, let's rely on people to decide their own health care," he said.

The debate was the last before the Iowa caucuses on Jan 3, and came in the midst of a remarkable period of turmoil in the race for the Republican presidential nomination.

Former Arkansas Gov. Mike Huckabee has eroded Giuliani's lead in nationwide polls, and he has overtaken Romney in public surveys of likely caucus goers in Iowa. The result has been an increase in testiness -- Romney on Tuesday became the first candidate to assail another in a TV ad, hitting Huckabee for his position on immigration.

But all nine men on the debate stage were on their best behavior in the opening moments of the 90-minute event, and the format offered little or no opportunity for a spirited exchange on immigration or any other issue.

Carolyn Washburn, the editor of The Des Moines Register, presided over a debate that was more like a recitation of long-held positions by the candidates than an attempt to highlight differences.

Former Sen. Fred Thompson of Tennessee was an exception on the question about spending cuts and sacrifice. "We've got to spend more for the military as a matter of fact, but we've got to look at Social Security and Medicare and do some things that won't hurt anybody badly," he said. Thompson, alone among the White House contenders in both parties, has called for steps to reduce the benefits promised to future retirees.

Washburn brought about a mini-revolt at one point when she asked all the candidates to raise their hands if they thought global warming was a serious threat caused by human behavior. "I'm not doing hand shows today," said Thompson.

Ultimately, no one disputed that it was a problem and humans at least contribute to it.

"I know it's real," said Sen. John McCain of Arizona, who advocates legislation to tackle the problem.

"Climate change is real. It's happening. Human beings are contributing to it," agreed Giuliani.

The debate was sponsored by The Des Moines Register and Iowa Public Television.

In the Register's latest poll, released Dec. 2, Romney has 25 percent support, Huckabee has 24 percent, Giuliani has 14 percent and Thompson has 12 percent.

But no one Republican presidential candidate is a shoo-in, according to recent polling by The Associated Press and the nonpartisan Pew Research Center.

Underscoring the tumult so far, only 57 percent of Republicans in Iowa said they strongly support their favorite candidate. That figure is even lower in New Hampshire, 49 percent, and South Carolina, 44 percent, in an indication that many have yet to make up their minds for good.

As for Giuliani, the former New York mayor is seen as the most electable candidate by Iowa and South Carolina Republicans and is tied with Romney in that category in New Hampshire. However, solid majorities in each state say that is less important than finding a candidate they agree with on the issues.