DENVER — Ben Carson, the retired neurosurgeon who has never held or run for elective office, is currently fourth in the RealClearPolitics average of national polls — ahead of five governors, four senators, one CEO and one billionaire. Carson has been climbing in the polls since he announced his candidacy on May 4. On the day before the announcement, Carson was at 4.8 percent in the RCP average; now, he’s at 9.4 percent.