Two national polls today show differing results; Romney is close in Florida and Virginia, but down in Ohio; Romney's gaffe was worse than Obama's; and the Democrat might be winning the Arizona senate race. Here's our guide to today's polls and why they matter. 

Findings: A National Journal poll has Obama and Romney tied at 47 percent each among likely voters, but an NPR poll has Obama with a seven point lead among them.
Pollster: United Technologies/National Journal Congressional Connection PollNPR/Democracy Corps/Resurgent Republic 
Methodology: For National Journal: Poll of 1,005 adults, including 789 likely votes, September 27 through 30 with a margin of error of +/-3.7 percentages points. For NPR: Poll of 800 likely voters September 26 through 30 with a margin of error of +/-3.46 percentage points.
Why it matters: The narrative we have seen this week is that the race is once again growing tighter. The National Journal poll would support this, and as Michael Tomasky said at The Daily Beast, Republicans are "touting" it. That said, while the NPR poll would seem to present a sunnier picture for Obama, Mara Liasson and Ron Elving write that "the poll also finds former Massachusetts Gov. Mitt Romney very much within striking distance of the incumbent as the two men begin a series of three debates Wednesday in Denver." 
Caveat: Tomasky explains that there might be something off with the National Journal's demographics. While their respondents are 74 percent white, matching up with the exit polls from 2008, a demographer has predicted that turnout among that group will drop. However, Tomasky has "a hard time seeing" black turnout dropping from 2008, which the Journal poll demographics appear to show it doing. 


Findings: Obama has a one point lead in Florida and a two point lead in Virginia among likely voters, but an eight point lead in Ohio. 
Pollster: NBC News/Wall Street Journal/Marist
Methodology: For Virginia: Poll of 969 likely voters September 30 through October 1 with a margin of error of +/-3.1 percent. For Florida: Poll of 890 likely voters with a margin of error of +/-3.3 percent. For Ohio: Poll of 931 likely voters with a margin of error of +/-3.2 percent.
Why it matters: Sara Murray writes in the Journal that these new polls show that the race is "highly competitive." That said, it's looking grim for Romney in Ohio, but the closeness of the other two races implies that if he loses that one he still has a chance to win in the states he would need. The question then becomes should Romney pull out of Ohio, but The New Republic's Nate Cohn cautions on Twitter: "If you want to know whether Romney can quit Ohio, don't just look at FL and VA, look at IA, NV, WI, CO, VA, FL." A Marquette University Law School Poll shows Obama up by 11 points among likely voters in Wisconsin.  
Caveat: A debate can change things around. 


Findings: As David Weigel points out, an NBC News/Wall Street Journal poll reveals that Romney's "47 percent" comments hurt more than Obama's "You didn't build that" among registered voters. Whereas 32 percent said their opinions of Obama were "more negative" after his verbal faux pas, 36 said their opinions were "more positive." As for Romney's "47 percent," 45 percent said their opinions were "more negative" and only 23 percent had a "more positive impression." 
Pollster: Democratic pollster Peter Hart and Republican Bill McInturff for NBC News/Wall Street Journal
Methodology: Poll of 1,000 registered voters September 26 through 30 with a margin of error of +/-3.10 percent.
Why it matters: As Weigel writes: "This poll's got a 32% Democratic, 20% Republican sample.  [As commenter mhwood points, in fact, Weigel's demographics are off. Counting both those who consider themselves "strong" and "not very strong" the poll would look to include 26 percent Republicans.] Can we safely assume that people who like Barack Obama like 'build that,' and people who dislike Obama don't? If so, sweet fancy Moses was the Republican convention ever a bust. " The RNC harped on "you didn't build that," but Romney's "47 percent" gaffe seems to have had a more lasting effect on voters. 
Caveat: Debates provide the opportunity for new gaffes.


Findings: Democrat Richard Carmona has taken a two-point lead over Republican Jeff Flake in a new Public Policy Polling poll of the Arizona state senate race. 
Pollster: Public Policy Polling
Methodology: Poll of 595 likely Arizona voters October 1 through 3 with a margin of error of +/-4 percent.
Why it matters: Even as Obama is down by nine points in the presidential race in the state, the Democratic senate candidate is taking the lead, at least according to PPP. Another recent poll doesn't necessarily show a Carmona lead, but does show a tight race.
Caveat: PPP leans left, but said in a tweet: "Obama's down by 9 on our Arizona poll even as Carmona leads by 2...not a crazy pro-Dem sample"