Mitt Romney cheered the coal industry in the presidential debates with his succinct declaration that “I like coal,” highlighting an issue that has divided the Republican nominee from President Barack Obama.

Mr. Romney singled out coal in describing his energy plan, saying, “I’m going to make sure we continue to burn clean coal.” He said the U.S. coal industry, which generates about 40% of the country’s electricity, feels like it’s getting “crushed” by environmental standards under the Obama administration.

Mr. Obama, who was on the defensive for much of Wednesday’s debate, didn’t respond directly to that attack, but he said that in general he wants to “boost American energy production.”

In the past, the president has said he supports coal when coupled with technologies that prevent emissions from escaping into the atmosphere. His administration has invested in the development of clean-coal technologies, but the most effective technologies are generally expensive and unproven.