Dr. Abdul El Sayed entered the Democratic Senate primary with the kind of polling advantage that makes consultants practice their victory speeches early. Michigan Democrats, it turns out, were not all eager to sign up for the revolution. El Sayed tried to cast the contest in sweeping terms, rejecting the idea that Michigan is divided between left and center. Republican Mike Rogers told The Post that he expected whoever emerged from the Democratic primary to face coalition problems. For Republicans, it offered a useful reminder that the left’s loudest voices do not always speak for the voters Democrats need most in November.