Obama: GOP field 'must have been founding members of the Flat Earth Society'

"We've heard this kind of thinking before. Let me tell you something. If some of these folks were around when Columbus set sail, they must have been founding members of the Flat Earth Society," he said to an enthusiastic crowd at Prince George’s Community College in Largo, Md.

Without naming names he also made reference to former House Speaker Newt Gingrich, blasting his $2.50 gas price pledge.

"This has been going on for years now and over time prices start to go up — especially in an election year, politicians dust off their plans for $2 gas, I guess this year they decided to make it $2.50. Why not $2.40, why not $2.10?" he said to laughter from the audience.

White House press secretary Jay Carney set up the president's argument against Gingrich Monday when he said that any politician who guarantees $2.50 at the pump "is lying."

Carney later walked back the attack, however, saying he shouldn't have ascribed "motivations" to Gingrich's promise.

The White House has continued to hammer the GOP contenders on energy issues.

Gingrich, who said he would drive gas prices down by expanding drilling further into offshore and federally-owned areas, told a campaign forum Monday night that his plan was threatening to Obama.

“I have suggested that if we developed our energy capacity to the degree we could, that that would bring down the price of gasoline on the theory that supply and demand works, and this is not something that Obama is very used to," Gingrich said.

Fellow Republican candidate Mitt Romney pounced on the issue Thursday just prior to Obama's speech, blaming the president for sending gas prices through the roof.

"The president has lots of places to point his finger and of course we alone don’t set world energy prices," said Romney on Fox News. "We can determine whether we have an effect on those energy prices by having an abundant supply here. The president has done all of that wrong. It has got to change."

The average national price for regular unleaded gas is $3.81, up from $3.51 a month ago, according to AAA's Daily Fuel Gauge Report on Thursday.

The Obama administration has been under pressure as rising gas prices threaten to derail the political gains he has made from recent positive economic news.

For more on Obama's energy policies check out The Hill's E2 Wire blog here.