Here’s a succinct example that might illustrate why voters seem to prefer Barack Obama over John McCain on economic issues.

Both campaigns released new ads this morning. McCain’s, which is Web-only, devotes 90 seconds to linking Obama to Bill Ayers ("Barack Obama. Too risky for America").

Obama’s ad attacks the mortgage-buying plan McCain first presented during Tuesday night’s debate. This morning, Mike Allen reported the plan underwent some changes last night "making it more generous to financial institutions and more costly for taxpayers." The release says the ad will be airing nationally.

Ayers has been one of the McCain campaign’s themes this week, although at various points it has looked like they weren’t going to talk about the ’60s radical anymore, probably because voters don’t seem to care that much.

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