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The New York Times voting and data guru Nate Silver estimates voter ID laws could reduce turnout by 2 to 3 percent in a state, a number that is smaller than some critics of these laws say but also large enough to shape outcomes in tightly-contested places.

In a piece, he predicts a new law in Pennsylvania, which requires people to have a photo identification in order to vote, could reduce Obama’s percentage of the vote there by more than 1 percent. That number is significant, George W. Bush won Florida in 2000 and Obama won North Carolina in 2008 by less than a percentage point.

At the same time, Pennsylvania is the only swing state with one of these laws currently in place and being enforced, and the president won the state by 10 points in 2008.

Related: Will Voter ID law in Pennsylvania hurt Obama?

“Although I do think these laws will have some detrimental effect on Democratic turnout, it is unlikely to be as large as some Democrats fear or as some news media reports imply — and they can also serve as a rallying point for the party bases,” he writes. ” So although the direct effects of these laws are likely negative for Democrats, it wouldn’t take that much in terms of increased base voter engagement — and increased voter conscientiousness about their registration status — to mitigate them.”