President Barack Obama's re-election campaign intensified its rebukes of Mitt Romney Friday, Aug. 24 evening for a remark made by the presumptive Republican nominee about the president's birth certificate earlier in the day, according to The Huffington Post.

Speaking to a crowd of enthusiastic supporters in Commerce, Mich. and noting the local roots shared by him and his wife, Ann Romney quipped that "no one's ever asked to see my birth certificate. They know that this is the place that we were born and raised." Of course, Obama's birthplace has been the subject of fervid (if wholly debunked) conspiracy theorizing in the years since he arrived on the national stage.

The Obama campaign responded with a 15-second attack ad posted to YouTube Friday evening titled "America Doesn't Need A Birther-in-Chief" that recycles video of Romney's joke, while a narrator intones, "Holding out hope Romney had a vision for the middle class? Think again."

The ad is the latest in a string of responses from the Obama camp to Romney's comment. First, a campaign spokesman slammed the Republican for "embrac[ing] the most strident voices in his party instead of standing up to them." Later, the president's official Twitter account followed with a barely veiled reference to the joke. The campaign also sent a fundraising email to supporters, with the subject line: "A new low for Mitt Romney."