In what might be his most controversial attack ad in a campaign dominated by them, presumptive G.O.P. presidential nominee John McCain today launched a new TV spot attacking Sen. Barack Obama (D-Ill)’s two children.

According to political insiders, a negative ad targeting a rival’s offspring is highly unorthodox, especially when the children in question are under the age of ten.

But after the two Obama kids scored in their performance on national television last night at the Democratic convention, “we had to do something to give the American people some straight talk on those two brats,” Sen. McCain said today.

In the ad, which is being broadcast in key swing states, an announcer intones, “They’re the cutest children in the world – but are they ready to lead?”

The spot uses visuals to link the two Obama kids to other famously cute kids, such as the young Drew Barrymore and the Cabbage Patch dolls.

The commercial goes on to blast the Obama children for “smiling and giggling but refusing to state their position on offshore oil drilling.”

While some critics questioned how well the ad would play in living rooms across America, Sen. McCain defended it, telling reporters, “It played very well in all of my living rooms.”