Obama's lead with women voters explains his national poll lead, McCaskill is up by just 1 point in her Missouri Senate race, and Obama is up by a whopping 11 points in a new poll out of Nevada. Here's our guide to today's polls and why they matter.

Findings: Obama has an 18 point lead among women in a new Quinnipiac University national poll.
Pollster: Quinnipiac
Methodology: Landline and cell phone interviews with 1,912 likely voters September 25 through 30 with a margin of error of +/-2.2 percent. 
Why it matters: From Ann Romney's "I love you women" to the "war on women," the female demographic has been oft-discussed and hotly contested in this election season. Quinnipiac attributes Obama's 18 point lead with women to his small lead in the national race among likely voters. Yesterday Ronald Brownstein at the National Journal attributed Obama's lead in swing states to a "surprisingly strong performance among blue-collar white women who usually tilt toward the GOP."   
Caveat: While the Quinnipiac poll gives Obama a slightly larger lead than some recent polls, it's still pretty tight in general. 


Findings: Claire McCaskill holds barely a 1 point lead over Todd Akin in the Missouri Senate race — 46 percent to 45.2 percent —in a We Ask America poll. 
Pollster: We Ask America
Methodology: Automated poll of 1,145 likely voters September 25 through 27 with a margin of error of +/-2.9 percent.
Why it matters: With the Republicans coming back into Akin's court, perhaps this once again is a hotly contested race, "legitimate rape" comments or no.  
Caveat: Nate Silver said in June that We Ask America's results often lean Republican, but in a post today said the pollster has been giving Obama " highly favorable trendlines" in a "recent set of state-by-state polls." Meanwhile, 8.8 percent are still undecided in the race. 


Findings: We Ask America has Obama leading in Nevada 52.5 percent to 42 percent. 
Pollster: We Ask America 
Methodology: Automated poll of 1,078 likely voters September 25 through 27 with a amrgin of error of +/-3.1 percent.
Why it matters: This is an enormous lead for Obama in a state, which just last week saw Obama up by only two points. In reference to that poll, Neil King Jr. of the Wall Street Journal wrote that "Democrats had predicted that Nevada would be safe Obama territory by now." 
Caveat: Same as above for We Ask America, also the Real Clear Politics Average puts Obama up by only 5.2 points