On the heels of a Gallup poll showing President Obama's lead among registered voters has disappeared since last week's debate, the Pew Research Center finds an even more stunning shift. Obama's eight-point lead with likely voters a month ago is gone; Mitt Romney now leads by four points. Among registered voters, Obama's nine-point lead has turned into a tie. 

Pew's likely voter group is 36 percent Republican, 30 percent Democrat and 30 percent Independent. Their last poll, in mid-September, found an electorate that was 29 percent Republican, 39 percent Democrat and 30 percent Independent. The shift is a sign of increasing Republican enthusiasm. The Fix explained last month why party ID varies from poll to poll. 

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