by Sean Bowditch

McCain hit the airwaves today with another ad, this time attacking Obama's Iran policy. The timing is key as the Democrats here in Denver — headlined by Veep nominee Sen. Joe Biden — prepare to spend the day discussing national security and foreign policy. The ad accuses Obama of misunderstanding and underestimating Iran's intentions in the Middle East.

McCain has used this line of attack repeatedly on the campaign trail: portraying Obama as dangerously unprepared and naive. It's clearly been effective among certain sectors of the population. As the new Quinnipiac poll indicates, many voters favor McCain — often by wide margins — when it comes to handling conflict, natural disasters, and bristly foreign relations. Hard to say at this early stage whether Biden's presence on the Democratic ticket will change that opinion.