Voters think President Obama will stand up for the middle class, but actual middle class voters are split between him and Mitt Romney. Meanwhile, Romney appears to be losing ground on Medicare. Here's our guide to today's polls and why they matter.

Findings: Obama leads Romney on the question of who stands up for middle class voters by 19 points — a 5-point jump from last month. But they're tied at 48 percent among people who describe themselves as middle class. That's three-fourths of voters.
Pollster: Politico/ George Washington University/ Battleground by the Tarrance Group and Lake Research Partners.
Methodology: Poll of 1,000 likely voters September 16 through 20 with a margin of error of +/-3.1 percent.
Why it matters: Does Romney's "47 percent" comment hurt him with the middle class? Depends on who you ask. Politico's Democratic analysts say, "Democrats still have room to translate their advantage on standing up for the middle class into votes" and advice them to keep attacking Romney on the comments. But Republican pollsters have their own optimistic (for them, at least) take on the demographic. They say: "In fact, on every measure it is Romney who is winning the battle for the support of middle-class families." Note the specificity: not the "middle-class" overall, but "middle-class families." Romney leads by 14 percent among middle class marrieds or those with kids at home.
Caveat: Last week polls evaluating how Romney's videotaped gaffe affected viewers noted that its unclear how opinions will translate into votes. These poll questions do not exactly test reaction to the comments, but we'll see if their effects linger come November.


Findings: A Gallup poll shows that, by a margin of 6 points, voters trust Obama when it comes to Medicare in swing states. And a tracking poll by Reuters/Ipsos finds that while Romney was beating Obama on Medicare the week ending September 9 by 41 percent to 30 percent, by September 16, the two were tied on the issue at 37 percent each among voters over the age of 60. That said, in Florida, the two candidates poll evenly on the subject.
Pollster: Gallup, Reuters/Ipsos, Mason-Dixon for Miami Herald/ Tampa Bay Times and other news orgnaizations.
Methodology: For Gallup: Telephone interviews with 1,216 adults in Colorado, Florida, Iowa, Michigan, Nevada, New Hampshire, New Mexico, North Carolina, Ohio, Pennsylvania, Virginia and Wisconsin September 11 through 17 with a margin of error of +/-4 percentage points. For Mason-Dixon: Poll of 800 likely voters September 17 through 19 with a 3.5 percent margin of error.
Why it matters: Romney's selection of Paul Ryan as his running mate made Medicare a much more prominent election issue, CBS News' Stephanie Condon points out. Anticipating the Obama campaign would attack Ryan's proposed changes to Medicare, Romney attacked Obama for cutting $700 billion from the Medicare budget. It worked, for a while. But in the case of the Reuters poll, the weakening of Romney's Medicare numbers translates into a weakening of his numbers among seniors. The Miami Herald, however, frames the Medicare numbers as good news for Romney explaining that Medicare is "a traditional Democratic strength."
Caveat: The Politico poll mentioned above gives Romney a 20-point lead among seniors, and noted that "only 7 percent of voters say Medicare and Social Security are the most important issues, exactly the same as in the last poll before the Ryan pick."