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Last night Bill Clinton said it would be "calamitous" if Mitt Romney were elected president. And this morning Bill O'Reilly called that "insane."

"All of these guys - it's amusing to me, and I'm sure it is to you, although you would never admit it. It's all a bunch of theater, it's guerrilla theater. They run around and they all [say] 'Romney is going to bring European socialism to the United States.' Does anyone believe that?" O'Reilly asked.

Although Clinton didn't use the word "socialism" in last night's private New York City fundraiser, he said Romney would be "calamitous for our country and the world" adding that Romney's economic policy is "austerity and unemployment now, and then a long-term budget that will explode the debt when the economy recovers so that interest rates will be so high nobody will be able to do anything."

O'Reilly questioned how Clinton could know Romney's policy would explode the debt. He said this election comes down to a very basic choice for voters.

"Look, the economy is terrible right now. And voters have to decide two things, whether they want to continue to go with Barack Obama's big top down government stimulation which has not worked so far. It might work, who knows," the host of the O'Reilly Factor on Fox News said. "Or do they want to change to a much leaner, meaner private sector driven economy. That's what the voters have to decide in November, simple as that."

A dismal jobs report Friday seemed to crystallize a new conventional wisdom that the race for president is tied, and Romney has a real shot at winning.

O'Reilly went a step further saying if the election were held tomorrow Romney would win because people are "afraid." But since there are still more than four months before votes are cast, O'Reilly says Romney needs to run a do no harm campaign because this is a referendum on Obama.

"If I were Romney I would get out of the way. I mean, don't be overbearing and he has to perform well in the three debates. He has to basically be calm, he has to put himself through it as authoritative, 'I'm going to solve these problems, alright? We gave the president three years, it's a mess. If you want to vote again on hope go ahead. But I have the ability to solve these problems,'" O'Reilly said.

O'Reilly's advice is for Romney to be "lower key" in the campaign and come on strong in the three debates, because that's one of Obama's strengths.