Mitt Romney’s tax and spending plans are so irresponsible, so cruel, so extreme that they are literally incredible. Voters may find it hard to believe anyone would support such things, so they are likely to discount even factual descriptions as partisan distortion.
The pro-Obama New Priorities PAC stumbled across this phenomena early in 2012 in its focus group testing. When they informed a focus group that Romney supported the budget plan by Rep. Paul Ryan (R-Wis.), and thus championed ending Medicare as we know it while also championing tax cuts for the wealthy, focus group participants simply didn’t believe it. No politician could be so clueless.