DES MOINES, Iowa (AP) — Dr. Ben Carson is appealing to Iowa conservatives with messages about securing the country’s borders and cracking down on employers who hire immigrants illegally. The retired neurosurgeon called for a harder tack on immigration, expanded school choice and less government spending in his speech Saturday to an Iowa gathering showcasing potential 2016 White House candidates. Carson spoke extemporaneously as he roamed the stage.

Carson is a former physician at The Johns Hopkins Hospital in Baltimore and author who is considering a run for the Republican presidential nomination. He has a following among conservatives for his harsh critiques of President Barack Obama’s health insurance law.

He told the crowd that he’s vehemently against the federal government diving further into health care. “Even if it worked,” he said, he would oppose it.