Michigan is a must-win for Romney because it's a state where his father was governor. But because it's an open primary, some Democrats may vote Republican, which could give Arizona Sen. John McCain a boost.
"We will create new jobs, we will have the ability," McCain said.
"If I'm elected president of this great land, I will not need a compass to tell me where Michigan is," said Romeny.
Both Romney and McCain are pledging to help Michigan's anemic economy. At 7.4 percent, Michigan has the highest unemployment rate in the country.
And advisers for both candidates say the Republican race will likely hinge on how many Democrats and independents end up voting in the Republican primary.
"I think for Romney, it's do or die," said Dick Simpson, UIC political science professor. "For Republicans, this is a meaningful contest. For the Democrats, it's totally confused and a mess, and they shouldn't have gotten themselves in this situation."
Simpson says for the Democrats, only former first lady Hillary Clinton is on the ballot because the state party kept moving Michigan's primary up earlier, causing a rift with the national party.
As Chicago Mayor Richard Daley made calls to voters for his candidate, Barack Obama both the Obama and Edwards campaigns are encouraging their supporters to vote 'uncommitted' in Tuesday's primary.
Michigan's Democratic Party chairman explained why on YouTube.
"If you vote uncommitted and uncommitted receives sufficient votes, delegates will be sent to the national convention who will be free to vote for whichever candidate they like," said Mark Brewer, Michigan Democratic Party.
But Simpson said he thinks that's too complicated for most voters. He suspects some Decmorats will vote in the Republican primary instead, which could mean a boost for the Republican carrying the momentum after winning New Hampshire, John McCain.
"McCain is the most appealing Republican candidate for Democrats and independents who are liberal or at least centrist," said Simpson.
So while Michigan means the most to Romney, the Democrats are focusing on Nevada, which is Saturday. Then it's on to South Carolina a week from this Saturday. And just three weeks from Tuesday is Super Tuesday, with 22 states holding primaries and caucuses, including Illinois.