“It’s shocking and insulting to be told before you go in to alter your testimony to what the administration wants,” he said. “This just shows a certain amount of amateurishness about how these hearings work. They’re supposed to be places where you get objective views. You don’t go around telling people what to say.”Mr. Jackson and the E.P.A. communications office did not respond to emailed questions about Mr. Jackson’s communications with Dr. Swackhamer.