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President Obama takes a (possibly) large lead in Paul Ryan's home state of Wisconsin, has a small lead in Virginia, but is tied with Mitt Romney in Colorado. In another poll of 12 swing states, Obama is up by two points. Here's our guide to today's polls and why they matter. 

Findings: One survey finds Obama leading Romney in Wisconsin by six points — 51 percent to 45 percent. Another finds Obama ahead by a whopping 14 points, at 54 percent to 40 percent. 
Pollster: New York Times/CBS News/Quinnipiac University, Marquette University Law School
Methodology: For the Times: Telephone interview of 1,485 likely Wisconsin voters September 11 through 17 with a margin of error of +/-3 percentage points. For Marquette: Telephone poll of 601 likely voters September 13 through 16 with a margin of error of +/-4.1 percentage points. 
Why it matters: Wisconsin is a traditionally blue state, but it had been getting more and more evenly split until 2008, when Obama won it by 14 points. The New York Times' Nate Silver gives Wisconsin a 9 percent chance of determining the Electoral College winner, while Jeff Zeleny and Marjorie Connelly explain that for Romney, "Wisconsin may be more essential than extra, a critical backup plan if a first-tier battleground state falls out of reach." The six-point lead "marks a slight shift" towards Obama since Ryan joined the Republican ticket. Talking Points Memo's Tom Kludt says just the Times poll lead was a "striking a blow to Ryan, whose economic pitch has centered around hardships in his hometown of Janesville."  The RNC has already responded to the Marquette poll, saying "President Obama’s upcoming visit to Milwaukee, paired with ad buys to be released next week show a President desperate to hang on to a state his campaign once thought was safely in their camp." 
Caveat: Marquette could be an outlier. National Journal's Steven Shepard explains that its lead is "well more than any other publicly released poll." The Real Clear Politics Average shows Obama's lead closer to the Times poll.


Findings: Obama is up by 4 points in Virginia according to the Times poll — 50 percent to 46 percent. Or he's up by about 3 points, according to a We Ask America poll showing the president with 48.5 percent to Romney's 45.7 percent. 
Pollster: New York Times/CBS News/Quinnipiac University, We Ask America 
Methodology: For Times: Telephone interview of 1,474 likely Virginia voters September 11 through 17 with a margin of error of +/-3 percentage points. For We Ask America: Automated poll of 1,238 likely voters September 17 with a margin of error of +/-2.8 percent.
Why it matters: These polls show Obama up by a much smaller amount than a Washington Post poll revealed yesterday, and Silver explains that  the "state has also been a headache for pollsters." because polls have been all over the place in the state. That said, this is the sixth straight poll showing Romney behind Obama in the state, The Hill's Cameron Joseph points out. If Obama wins Virginia, the electoral math gets much tricker for Romney.
Caveat: Zeleny and Connelly point out that the results are within the margin of error. 


Findings: Obama leads by only 1 percent in Colorado in the Times poll. 
Pollster: New York Times/CBS News/Quinnipiac University 
Methodology: Telephone interview of 1,497 likely Colorado voters September 11 through 17 with a margin of error of +/-3 percentage points.
Why it matters: Just yesterday a Rasmussen poll showed Romney up by two in the state. That said, even though Obama barely leads in the Times poll, he's turned the tables from early August when Romney led by 5 points in the state. 
Caveat: The results for the Times poll are within the margin of error.


Findings: USA Today/Gallup poll has Obama up by two points — 48 percent to 46 percent — among registered voters in 12 swing states.  
Pollster: USA Today/Gallup 
Methodology: Telephone interviews of 1,096 registered voters September 11 through 17 in Colorado, Florida, Iowa, Michigan, Nevada, New Hampshire, New Mexico, North Carolina, Ohio, Pennsylvania, Virginia, and Wisconsin with a margin of error of +/-4 percentage points.
Why it matters: The race "may be reverting to its more competitive equilibrium," according to Gallup. However, they add: "The fact that the swing-state vote is competitive, with at least a slight advantage for Obama each month since March, may mean Obama is currently in a stronger position to win than is Romney." 
Caveat:  The Washington Post 's Aaron Blake notes that "While Gallup continues to show a very close race nationally and in swing states, other pollsters are continuing to show Obama with a slight but noticeable edge." But Gallup says that conditions could actually be more favorable for Romney, because its poll was of registered voters, not likely voters, and Republicans turn out at a higher rate. On the other other hand, Pew Research Center finds a spike in enthusiasm among Democrats.

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