Obama ad hits Romney on taxes (yep, again)

Welcome to Pennsylvania, Mitt Romney! What are you hiding? That's the message in the latest Obama campaign ad to take aim at the Republican standard-bearer's personal finances to make the case that he cannot be trusted to steer the economy.

The ad accuses Romney of having "used every trick in the book" to shrink his tax burden and says it "makes you wonder if some years he paid any taxes at all."

"We don't know because Romney has released just one full year of his tax returns and won't release anything before 2010," the ad says. "What is Mitt Romney hiding?"

The Obama campaign has been attacking Romney's personal finances as a way of blunting criticisms of the president over the fitful economy, and casting doubt on the former Massachusetts governor's credentials. Romney has declined to follow longstanding precedent by releasing a decade's worth of tax returns, a fact Democrats have gleefully turned into ammunition for election-year assaults. And even some Republicans have called for Romney to release his returns—calls he has rejected.

Here's what Team Romney isn't hiding: Their contempt for this line of attack.

"With no rationale for re-election and no plan to help middle-class Americans, President Obama has resorted to running a campaign of distraction, distortion and dishonesty," spokeswoman Andrea Saul said in a statement.