“The 2012 playing field is much closer to 2008 than 2004,” Democratic strategist Tad Devine said. “In fact, Obama has many more targets than [Vice President Al] Gore or Kerry.”

What would mess up that math for Democrats, however, is if Obama were not able to hold some of the states that backed both him and Kerry .

The epicenter of that potential Democratic problem is in the Rust Belt, where an aging white population, the continued struggles of the manufacturing economy and large numbers of rural voters could make for a dangerous electoral brew.

Taken together, Michigan, Pennsylvania and Wisconsin will award 46 electoral votes in 2012. No Republican since George H.W. Bush in 1988 has won Michigan or Pennsylvania, and Ronald Reagan was the last GOP presidential candidate to win in Wisconsin, in 1984.

But there have been close calls in the not-so-distant past.