Fox News poll: McCain nets five points since last week, now within three; Update: Sample bias?

A little good news to balance the two-point bumps The One got today in Rasmussen and Gallup. The five-point gain overall coincides with a five-point gain among Republicans, only 83 percent of whom were committed to Maverick last week. Is the Joe the Plumber rhetoric working? Maybe, maybe not:

The economy continues to far outdistance all other issues as the top priority for voters this year, and while Obama maintains an advantage on the economy, McCain has chipped away at those numbers. By an 8-point margin Obama is seen as the candidate who voters trust to handle the economy, down from a 15-point edge

More voters trust Obama to handle the issue of taxes (+6 points) even though nearly three times as many think their taxes will go up under an Obama administration (20 percent) as think the same about a McCain administration (7 percent).

Amazingly, Rasmussen now has McCain ahead on both issues — and yet still trailing outside the margin of error. I don’t know how to reconcile those two data points given the emphasis on the economy, unless it means most people have made up their minds and are sticking with their guy even if their preference for him on particular subjects momentarily falters.

Unambiguous good news: After weeks of trailing, two new polls suddenly show Norm Coleman ahead of Franken, thanks mainly to indie candidate Dean Barkley peeling liberals away from the joke candidate. (According to NBC, Franken’s net favorables are negative.) If you have some coin to spare and haven’t given it to Bill Russell, here’s Coleman’s donation page.

Update: Dave Weigel of Reason e-mails with a possible explanation for the McCain gain: Last week’s poll used a sample of 43% Democrats and 37% Republicans; this week’s is 41% Dem and 39% GOP. It’s possible, I guess, that the new sample more accurately reflects the composition of the electorate, but I’m skeptical.