Two new polls out today show Rick Santorum leading Mitt Romney in Michigan, the state where the former Massachusetts governor was born and believed to have an advantage.

An American Research Group poll shows Santorum, a former Pennsylvania senator, leading Romney 33% to 27% among likely GOP voters. Santorum's lead over Romney is 15 percentage points in a Michigan survey by Public Policy Polling.

The Michigan primary is Feb. 28.

Romney has close ties to the state, where his father was head of American Motors Co. in the 1950s and governor in the 1960s. Romney even kicked off his 2008 presidential campaign in Michigan and easily defeated Arizona Sen. John McCain in the GOP primary there four years ago.

Santorum routinely stresses his blue-collar roots, which could play a key role as the GOP race moves to Rust Belt states like Michigan and Ohio. After his three-state victories last week, Santorum said he believes he could do "exceptionally well" in Michigan and Arizona, the next two states to vote.

Newt Gingrich is at 21% and Ron Paul is at 12% in the American Research Group survey. They are flipped in the Democratic-leaning PPP survey, with Paul at 12% and Gingrich at 11%.