Nobel laureate economist Paul Krugman has never shied away from expressing his distaste for Republicans, and he's certainly not holding back now.

What many Republicans have done "when faced with inconvenient facts [about the economy is to] resort to conspiracy theories," he writes in The New York Times.

Obamacare care is one example, he says. "Before Obamacare went into effect, they overwhelmingly insisted that it would be a disaster. . . . But problems were fixed, and enrollment soared. Their response? 'They are cooking the books,' declared Sen. John Barrasso, R-Wyo."

Then there was the criticism of former Fed Chairman Ben Bernanke. "The inflation [some Republicans warned against] never materialized, and the dollar proceeded to strengthen," Krugman says. But, 'Many conservatives . . . insist that the government is hiding price rises."

Much of the GOP is inflexibly clinging to economic dogma, Krugman says. "We can’t have meaningful cooperation when we can’t agree on reality, when even establishment figures in the Republican Party essentially believe that facts have a liberal bias."

Many analysts expressed great enthusiasm about the economy following Friday's strong employment report for December — job creation last year was the highest since 1999.

Meanwhile, another Democrat, former Treasury Secretary Larry Summers says he isn't satisfied with the economy's performance. "We're doing much better than we were. We're doing much better than the rest of the world. But we're not doing well enough," he told CNBC.

"We haven't had a year of 3 percent growth in a very long time in the United States. And if you look at what the bond market is saying, with interest rates coming down as much as they have, it suggests continuing concern about underlying growth in this economy."

Growth averaged 2.5 percent in the first three quarters of 2014.

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