Ben Carson, a retired neurosurgeon who has never held elective office, said on Sunday that he would seek the 2016 Republican nomination for president, joining the party’s fast-growing field.

Mr. Carson, who appeared on the political scene just two years ago and gained attention among conservatives for a speech highly critical of President Obama, planned a formal announcement of his candidacy on Monday in his native Detroit. He began his rise from poverty there to the heights of medicine — a path that shaped his rejection of liberal social policies in favor of self-reliance.

On Sunday evening, Mr. Carson said in an interview with a Washington television station that he was entering the race. “I’m announcing my candidacy for president of the United States,” he told WJLA.