Polls: Romney, Santorum neck and neck in Michigan

New polls show Mitt Romney and Rick Santorum are deadlocked in Michigan, on the eve of a pair of key primaries that will boost their claims to the GOP presidential nomination. Romney has a slight lead in surveys released Sunday by Public Policy Polling and We Ask America in his native state of Michigan, while Santorum is ahead in the poll by Mitchell Research/Rosetta Stone. STORY: Swing states poll INTERACTIVE: Poll tracker The former Massachusetts governor is on more solid ground in new polls out of Arizona, which also holds its primary tomorrow. Michigan, with 30 delegates at stake, is the larger prize and a key swing state that will also factor in the general election. Ron Paul and Newt Gingrich trail the two leaders in both states, according to the latest polls. Romney leads Santorum, 39% to 37%, among likely GOP primary voters in the PPP survey in Michigan. He's ahead by about 4 percentage points in the We Ask America survey. The Mitchell poll, meanwhile, has Santorum leading Romney, 37% to 35%, among likely GOP voters. In a key finding, Santorum's popularity among GOP voters has taken a nose dive in the PPP survey. His net favorability ratings have dropped 29 percentage points. And in a state that's been hard hit by the recession, Romney leads Santorum by 15 points in the PPP survey among those Michigan voters who say the economy -- and not social issues, as Santorum has stressed -- is their top concern. "Momentum in Michigan is completely on Mitt Romney's side," said Dean Debnam, president of Public Policy Polling. "He's amassed a large lead with absentee voters and it will take a huge turnout on Election Day from Santorum voters to overcome that." The Mitchell poll shows Santorum doing best among evangelical voters, Tea Party supporters, and those voters who describe themselves as the most conservative. "Santorum's strong appeal to social conservatives has been very effective," Steven Mitchell of Mitchell Research told the Detroit Free Press. "This race is still very close, but momentum seems to have changed. Get-out-the-vote efforts will really count." Final polls are likely to be released later today.