Poll: Obama up by four in Iowa

President Obama leads Mitt Romney by four points in Iowa, according to a new poll conducted for the Des Moines Register.

Obama leads Romney by 49 to 45 percent in the poll, which is widely considered to be the most reputable one of the state. It comes on the heels of a number of Iowa polls with widely varying results: in the past week, polls have shown Obama with as high as an eight-point lead there, and Romney with a three-point lead.

While the state has only six electoral votes it could prove a must-win for Romney, especially if he's looking for a replacement for Ohio, which increasingly looks like it's leaning toward Obama.

Both candidates are well-known in the state: Obama won its Democratic caucuses four years ago, launching his campaign, while Romney competed heavily in its GOP caucuses both last year and four years ago, falling just short both times. As a result, only 2 percent of voters in the poll are undecided, though one in 10 say they could still switch their vote.

The poll of 650 likely voters was conducted from Sept. 23-26 by the respected Selzer & Co., and has a margin of error of 3.8 percentage points.

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