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A fib is a fib is a fib.

Unless you're President Obama.

Nobel Prize-winning economist Paul Krugman, speaking on ABC's "This Week" on Sunday, ripped into Mitt Romney for telling "flat-out untruths" at last week's debate.

But when asked about Obama's on-stage misstatements, The New York Times columnist called them just "minor fudges."

The discrepancy drew a pronounced "Ugh" from Republican strategist Mary Matalin, a panel member who later told Krugman: "You are hardly credible on calling somebody else a liar."

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Krugman's initial gripe with Romney was that he said during the debate in Denver that his health care proposal would cover people with pre-existing conditions.

Romney's plan partially does that -- what Romney didn't mention on stage was that a person would have to have continuous health coverage in order to keep coverage in the face of a pre-existing condition.

"The press just doesn't know how to handle flat-out untruths," Krugman complained.

Fact-checkers actually did flag that Romney statement post-debate, but they also flagged several Obama statements. Among them was Obama's dubious claim that his budget plan would cut the deficit by $4 trillion over 10 years. That number includes some accounting tricks, including counting $1 trillion in already agreed-upon cuts.

ABC's Jonathan Karl pointed out to Krugman that "Obama also was loose with the facts."

"They were minor fudges," Krugman said.

"He said he had a $4 trillion plan to cut the deficit.  ... He said health care premiums were rising at the slowest rate in 50 years -- neither of those was true," Karl said.

Krugman again asserted "those are minor compared with" Romney's statements.