Click here to watch "Ready."

Call it the Swift Boat reflex. As an indication of the speed at which presidential contenders now feel compelled to respond to attacks, consider that it took less than six hours for John McCain to release a Web ad rebutting Hillary Rodham Clinton's latest TV spot in Pennsylvania, which portrays him as an unfit steward of the national economy.

Using the same footage as Clinton's ad -- with a shot of a steely-eyed McCain tacked on to the end -- "Ready" opens with the now-familiar line, "It's 3 a.m., and your children are safe and asleep." It then goes on to blast both Clinton and Barack Obama for their economic proposals, saying "they'd solve the problem by raising your taxes. More money out of your pocket. John McCain has a better plan: Grow jobs. Grow our economy, not grow Washington."

Although aides said the campaign plans to run the counterattack on TV, they virtually assured that the Web ad would receive valuable minutes of free play in the media by following so closely on the heels of Clinton's ad and borrowing her attention-grabbing "3 a.m." imagery. Besides defending McCain's economic bona fides, the spot could succeed simply by keeping the Republican candidate in the news and out from under the shadow of his two dueling Democratic opponents.

In addition to deploying the well-worn Republican charge that Democrats will raise taxes and expand the government, the spot will likely earn points with Republican voters as proof that McCain will respond forcefully to attacks from the other party. That mentality might explain why, as the New York Times reported yesterday, McCain adviser Steven Schmidt "said that the only call Mrs. Clinton would be taking at 3 a.m. was one telling her that she had lost another superdelegate."