(CNN) -- GOP presidential front-runners, locked in a tight race, pledged to help turn around Michigan's struggling economy in a last-minute effort to win over voters on the eve of the state's primary.
Mitt Romney sits in a Chrysler ecoVoyager during the Detroit Auto Show on Monday.
Going into the primary Tuesday, former Massachusetts Gov. Mitt Romney has a narrow lead over Sen. John McCain, according to recent polls of the state's Republican primary voters.
On Monday, Romney, McCain and former Arkansas Gov. Mike Huckabee toured the Detroit Auto Show, highlighting the economic problems of the struggling auto industry.
Michigan has one of the highest unemployment rates in the country -- 7.4 percent, compared with 5 percent nationally -- and the top-tier Republicans have vowed to make the revival of Michigan's economy a top priority.
"I want to bring Michigan back," Romney said Monday. "I'm not willing to sit back and say, 'Too bad for Michigan. Too bad for the car industry. Too bad for the people who've lost their jobs; they're gone forever.'
"That's not the kind of pessimism I think that'll make Michigan strong again. I will not rest, if I'm president of the United States, until Michigan is brought back."
While speaking to the Detroit Economic Club on later on Monday, Romney told business leaders, "What Michigan is feeling will be felt by the entire nation unless we win the economic battle here."
"Michigan is a bit like the canary in the mineshaft. What's hurting Michigan," he continued, "will imperil the entire nation's economy."
Some political analysts have said the state is a must-win for Romney, a Michigan native whose father was governor of the state in the 1960s.
During the first nine days of January, the Romney campaign spent more than $2 million in advertisements on television and radio in Michigan, compared with McCain's $359,000 and Huckabee's $39,000. Watch the fierce ad wars in Michigan »
Romney's campaign also announced it was pulling paid media in other early-voting states and focusing its remaining resources in Michigan.
Still, Romney said the state is "not do or die."
"We are going all the way through February. But I can tell you, it is very important to me. ... I would like to see Michigan in the win column."
McCain is hoping to re-create his 2000 victory in Michigan when he beat then-Texas Gov. George W. Bush by convincing independents and even Democrats to vote for him in the GOP primary.
There is no party registration in Michigan, and registered voters can cast their ballots in any primary. Since national party penalties have meant that most of the Democratic presidential field are not on the ballot -- and none of the major candidates will be campaigning in the state -- Democrats and independents may play a far greater role in Tuesday's GOP primary than they usually would.
McCain told voters Monday he thought focusing on "green technology" could revive Michigan's economy, saying that switching to alternative fuel sources is also an issue of national security.
"We are sending $400 billion of your dollars a year to oil-producing countries and look at those countries. They're not our friends," McCain said in Kalamazoo. "Some of that money's going to end up in the hands of terrorist organizations."
The senator from Arizona also said it's unrealistic to think all jobs can be restored, and he instead focuses on the retraining of workers.
"I would be ashamed to tell the people of Michigan or South Carolina that all of these jobs are coming back. I won the New Hampshire primary because I told people the truth: what they wanted to hear, what they didn't want to hear. These people know that a lot of these jobs aren't coming back," McCain said over the weekend.
Romney and McCain had some fierce exchanges before the New Hampshire primary, and the two camps continue to spar as they battle for votes in Michigan and South Carolina -- which holds its primary on January 19.
While in Kalamazoo, Michigan, McCain defended a mailing sent out in South Carolina that attacks Romney's record, saying it was not "negative campaigning" but a defensive measure.
"Now, we won't go tit-for-tat, but we will respond, and we will make clear that this kind of negative campaigning didn't work for him in Iowa when he attacked Gov. Huckabee, didn't work in New Hampshire when his campaign attacked me, and I don't think it's going to work in Michigan where he's attacking me, and it won't work in South Carolina," McCain said.
Huckabee hadn't campaigned in Michigan until last week, but just as in the Iowa caucuses, a grass-roots network of conservative Christian activists and "fair tax" proponents could keep him in contention for the top spot. Watch Huckabee call for the U.S. to become energy-independent »
Huckabee said Monday he would help Michigan's unemployment rate by enforcing "fair" trade agreements with China and other nations that export into the United States and by cutting regulations on business.
"I think we can bring a lot of these jobs back," Huckabee said, "but part of it starts that our free-trade agreements have to be fair trade agreements. They're not. The Chinese dump products on us that have lead in them. Some of the products they have aren't safe. We aren't enforcing our trade agreements in a manner in which we should so there's an unfair competition."
The former Baptist preacher again is emphasizing a populist economic message, saying it's time to "reset" the Republican Party.
"We've lost our soul," Huckabee said. "It's time that we regain it, remind ourselves what made us a strong party, strong national defense, conservative fiscal policies. But it's also a commitment to those issues of the family and the working class people of this country who are the bread and butter every day of this nation's economy."
Recent polls show Romney with a narrow lead over McCain in Michigan.
Twenty-eight percent of people likely to vote in Tuesday's GOP primary said they supported Romney, compared with 26 percent for McCain, according to an average of four polls.
Huckabee is third with 17 percent, followed by former New York Mayor Rudy Giuliani and former Sen. Fred Thompson of Tennessee with 5 percent each, according to the polls' average.
The latest results are based on four polls conducted after the New Hampshire primary: American Research Group, McClatchy/MSNBC/Mason-Dixon, Detroit Free Press/Local 4, and Detroit News/WXYZ-Action News.
The polls had a margin of error of plus or minus 4 to 5 percentage points. E-mail to a friend
CNN's Peter Hamby, Alexander Mooney, Rebecca Sinderbrand, Mary Snow and Alexander Marquardt contributed to this report.