Are Michigan and Pennsylvania swing states again?

Are Michigan and Pennsylvania in play again?

Polls published Tuesday in the two historically purple states show that the races, which a couple of weeks ago appeared to be firmly in President Obama's grip, are now up for grabs.

Obama's 10-percentage-point lead over Mitt Romney in Michigan has dropped to 48% to 45%, according to a poll of 600 likely voters conducted by EPIC-MRA. The gap between Obama and Romney was within the poll's margin of error. Obama also held a 49%-46% lead in Michigan in a Fox News 2 Detroit poll published Tuesday that was conducted two days after his dismal performance in the first presidential debate.

Meanwhile, in the electorally rich state of Pennsylvania, Obama is now leading 43%-40%, according to a Sienna Research Institute poll published Tuesday. Obama won the state by 11 points over Sen. John McCain in 2008.

Michigan and Pennsylvania haven't received a great deal of advertising attention from either campaign. Romney hasn't spent a dime on advertising in either state, and Obama has spent less than $5 million in Pennsylvania, according to an analysis of advertising spending by National Journal.

Like Romney, the Obama campaign hasn't spent any money on advertising in Michigan.