Memo to congressional Republicans: You might want to stray from GOP talking points and stick to the facts when facing off against a Nobel Prize-winning economist unless you want to be called out for falsehoods.

Tea party-backed Wisconsin Sen. Ron Johnson learned that the hard way Sunday during a heated panel discussion on ABC’s “This Week with George Stephanopoulos” in which he was accused by New York Times columnist Paul Krugman of getting the facts wrong on Social Security.

The debate began when Johnson said Social Security was in danger of “going broke” unless action was taken. “When I hear people saying Social Security is solvent to the year 2035, it’s not,” Johnson said.

Krugman replied, “You said ‘let’s start with the facts,’ but we’ve just run aground right there. Your facts are false. The Social Security thing — Social Security, it has a dedicated revenue base, it has a trust fund based on that dedicated revenue base. You can’t change the rules midstream and say, ‘Oh well, suddenly the trust fund doesn’t count.’ ”

Johnson countered that “the trust fund is a fiction. It doesn’t … it has no value in the federal government.”

Krugman responded, “It is important to realize that the facts that are being brought out here are, in fact, non-facts.”

The New York Times columnist later took to his Conscience of a Liberal blog after the contentious exchange to again excoriate the Wisconsin senator and other conservatives in the GOP. “I’ve explained this one over and over again, for example here,” he wrote. “And I have to say, it’s extremely telling that conservative Republicans don’t seem able to make their case without resorting, right from the beginning, to obviously dumb fallacies.”

Think Progress also noted, “The Social Security trust fund is solvent through 2038, and the program would almost certainly have long-term solvency were it not for the Republican-backed cap on payroll taxes for income above a certain level.”

— Posted by Tracy Bloom.