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New IA poll: Undecided takes the lead

From NBC's Mark Murray
A new Mason-Dixon poll shows that Clinton, Edwards, and Obama are all in a dead heat in Iowa. But the actual leader in the survey is someone who isn't even running -- and isn't even a person: It's "undecided".

In the poll -- which was taken of 400 likely Democratic caucus-goers from June 13-16, and which has a margin of error of +/- 5% -- Clinton is at 22%, Edwards is at 21%, and Obama is at 18%. Richardson comes in fourth at 6%, and Biden gets 4%; no other Dem gets more than 2%. But a whopping 27% say they are undecided.

On the Republican side, Romney has the clear lead at 25% (even over "undecided," which checks in at 21%). He's followed by Thompson at 17%, Giuliani at 15%, Huckabee at 7%, and McCain and Brownback at 6% each.

With the caveat that the caucuses are seven months away, the big winners in this Iowa poll are Romney (who's leading the GOP pack) and Clinton and Obama (who both seem to have a clear shot at taking this contest). The losers? Edwards (who needs to be ahead in Iowa) and McCain (who finishes tied for fifth with Brownback).