By Stephen Power and Laura Meckler

It’s not every day that the White House takes off after a member of Congress. Then again, it’s not every day that a member of Congress apologizes to an oil company responsible for a massive environmental and economic disaster.

On Thursday, Rep. Joe Barton of Texas, a senior House Republican, apologized to oil giant BP on behalf of the U.S. government, saying the company had been the victim of a “shakedown” engineered by the White House. He was referring to the $20 billion that BP agreed on Wednesday to put into a compensation fund for victims of the Gulf of Mexico oil spill, following hours of negotiations between BP and the White House.

Mr. Barton, speaking at a hearing of the House Energy and Commerce Committee, where BP CEO Tony Hayward was testifying, said the agreement set a “terrible precedent” and that he was “ashamed of what happened in the White House.”