Updated 10:07 a.m. - ATHENS, OH – Energized by a huge crowd and, likely, his improved debate performance against Mitt Romney Tuesday night, President Barack Obama went on an extended riff during remarks here about what he said was Romney’s inauthentic support for coal energy.

Noting that Romney praised coal during the debate at Hofstra University, Obama pointed out that as governor of Massachusetts, Romney appeared in front of a coal factory to criticize its high level of toxic pollution, saying, “that plant kills people.”

Obama said voters should be skeptical of Romney’s embrace of coal, mocking him as “running around talking like he’s Mr. Coal,” as a crowd of 14,000 at Ohio University cheered him on.

“Does anybody ever actually look at that guy and think, man, he’s really into coal?” Obama asked the audience as he chuckled.

Obama then brought up an ad, released earlier this week, that showed Romney speaking to workers at an Ohio coal mine, saying the workers in the ad were forced to attend the August Romney event – which the mining company and some of the workers have refuted.

“Did you see when he was doing that ad, he was in front of all those guys – all these miners with hard hats. Find out later they had to come. Boss made them come. Come on, gotta be on the level if you want to be the president of the United States!” he exclaimed.

The Romney campaign responded to the president's remarks in Athens by releasing a statement from spokeswoman Amanda Henneberg. "“As we approach Election Day, President Obama’s rhetoric and personal attacks will not mask a failed record that has left middle-class families hurting.  Under this President, permits for drilling on federal lands have declined, over one hundred coal-fired plants are schedule to close by the end of the year, and gas prices have more than doubled.  Mitt Romney has an all of the above energy strategy, which will create millions of jobs and put our nation on a course toward North American energy independence by 2020.”

Obama returned to the White House on Wednesday night. He heads to New Hampshire Thursday before taping "The Daily Show with Jon Stewart" in New York City.