As Ron Paul prepares to exit politics at the end of this year, the Texas Congressman's Keynesian nemesis Paul Krugman has already set a target on Paul's progeny, Kentucky Senator Rand Paul.

The Nobel Prize-winning economist has been feuding with Sen. Paul since Sunday, when the pair got into an argument over the size of the federal government payroll during a roundtable appearance ABC's This Week.

The debate, posted below, is a familiar one, centered around the relative merits of government stimulus spending. The key part comes around the six-minute mark, when Paul asks Krugman if he is arguing "that there are fewer government employees under Obama than there were under Bush."

"That's a fact," Krugman told Paul. "That's a tremendous fact."

Since then, Krugman has been hammering Paul over the exchange, even penning a scathing blog post titled "The Zombie That Ate Rand Paul's Brain."

Citing the liberal blog Think Progress, Krugman claims Paul "was completely shocked" by the assertion that government employment had fallen under Obama.

"Almost surely it's a case of a zombie lie that has gone unchallenged in the hermetic world of movement conservatism, so that people like Paul know, just know, something that ain't so," Krugman writes. "He wouldn’t have made this mistake if he ever read or listened to an analysis from nonpartisan sources, but he evidently doesn’t."

Setting aside Krugman's hyperbolic characterization of Paul's "shock," the problem with his argument is that it overlooks the fact that he and Paul were actually talking about two different sets of employment numbers. Paul was referring only to federal employment, which has risen by about 143,000 jobs under Obama, according to the Bureau of Labor Statistics. Krugman, on the other hand, is talking about the entire public sector — including state and local government payrolls — which has contracted during Obama's years in office.

"The only logical number we could have been discussing was the number of federal workers," Paul told Business Insider Monday. "We were talking about President Obama, and President Obama is in charge of the federal government. He's not the governor of New York, or the governor of Texas."

It's worth noting that, during the roundtable, Paul never explicitly says he is talking about federal employment. And some would argue that the loss of state and local government jobs is due, at least in part, to federal policies that have cut funding aid to states.

Paul, however, claims that Obama doesn't deserve the credit (or blame, depending on which way you look at it) for the choices states make in order to balance their budgets as required by law.

"States don't have a printing press, so they have to watch what they spend. They made the decisions they had to make," Paul said. "Krugman is insulting the intelligence of his readers by telling them that President Obama had anything to do with it."

"Krugman believes in government trickle-down," he continued. "It's an important point in the difference of the visions of President Obama and Republicans. He [Obama] thinks, and Paul Krugman thinks, that you can get yourself out of a recession is by spending more. But if you want to stimulate the economy, the most efficient way to do it is not through government."

Krugman, a vocal proponent of deficit spending, would likely have a response to this argument. But by misrepresenting Paul's positions — and basically accusing him of being brainwashed — the New York Times columnist missed the opportunity to have a real debate. Regardless of where you fall on the Keynesian spectrum, it's pretty clear Paul is not simply spouting Republican "zombie" talking points — as evidenced by the fact that, earlier on the This Week segment, the Kentucky Senator agreed with Krugman that Republicans have been "inconsistent" on defense budget cuts by "accepting Keynes with regards to military spending but not domestic spending."

Still, Paul seems to be taking it all in stride.

"I can tell you this about Paul Krugman — he's a lot nicer in person than he is on Twitter," Paul said, smiling. "To say that my brain has been eaten by zombies — that's just not nice. Nor is it true."

Watch Paul and Krugman on This Week below: