A new NBC/Wall Street Journal poll came out yesterday that did something very interesting: it tested likely general-election attack-lines on the three surviving presidential candidates.

Respondents were asked how concerned they were about McCain's age, history of flip-flops, and closeness to George W. Bush. For Clinton, they were asked about her own perceived flip-flops, her honesty, and the role that her husband might play in her administration. And for Obama, they were asked about his patriotism, his closeness to controversial figures like Jeremiah Wright and William Ayers, and his "bittergate" comments.

A site called FiveThirtyEight.com has published a nifty chart that ranks the results on these "concerns," and also compares them to the media coverage of each. You can read it yourself, but the basic finding was that Hillary's alleged flip-flops and McCain's closeness to Bush and alleged flip-flops rank at the top, while McCain's age, Hillary's relationship with her husband, and Obama's supposed lack of patriotism rank at the bottom. The last two items have obviously received a lot more media attention than public concerns might justify--not to mention the massive media coverage of "bittergate" and Wright, which stimulate concerns about Obama that rank in the middle of the scale.

It's probably worth observing that "flip-flop" concerns about HRC and McCain may be misleading since some of those respondents voicing them are probably strongly progressive or conservative voters who in the end won't defect to the opposition candidate. Conversely, McCain's age could become a hotter topic during the discussion about his running-mate choice (a big deal to conservatives in particular due to concerns that McCain might be a one-term president), and would definitely draw attention if it's reinforced by some incident like Bob Dole's famous fall from the platform in 1996.

Interesting as they are, these findings don't really get at the sort of meta-attacks that stitch together these and other "voter concerns." It's already obvious that the GOP plans to hammer Obama as an inexperienced dilettante who's out of touch with the political and cultural mainstream; and Clinton as a divisive and dishonest ideologue who will perpetuate the savage political climate of the recent past. For McCain, the conjunction of concerns about "flip-flopping" and closeness to Bush is potentially toxic. If Democrats succeed in defining McCain as a man who is constantly reinventing himself to disguise his desire to continue Bush's deeply unpopular policies and champion a deeply unpopular GOP, the Straight Talk Express could hit some major potholes.