Bill Lucas' manner is mild as milk. His speech is touched, as softly as by a Caribbean breeze, with the lilt of St. Martin, where he was born. This faint, musical inflection survived a Harlem childhood, during which both parents died within a year. His voice will resonate nationally next year when he tries to become America's first black governor. His attempt will have added drama because he was a Democrat until earlier this year, and now is running as a Republican.

Lucas is a 57-year-old with four grandchildren. He looks 45 and carries himself with the gliding grace of a distance runner, which he was in college. He has transmitted the discipline of the track to five children: a policeman, three doctors and one medical student.

Fresh from Fordham Law School, he joined Robert Kennedy's Justice Department, then became an FBI agent. He settled in Detroit.

In 1968, the year after the riots, he became undersheriff of Wayne County, which contains Detroit and 2.3 million people -- one-quarter of Michigan's population. It is the nation's fourth most populous county. He became sheriff in 1969 and served until 1983, when he became the first elected county executive. Not bad for a man who says that few of the boys he knew in Harlem are still alive.

"I am," he says, "a fairly good judge of human nature, having spent my life on the streets." There is, he says, "nothing extraordinary" about his ideas for "an orderly society," such as: "If you keep doing something for people, they will continue to expect it." He believes that the form of discipline called patience is as important as intelligence. He runs a closely supervised youth jobs programs because "the ethics of work follow you all your life."

Even more than his words, his works cause Republican pulses to race. For example, by measnty hospital over to private operation he cut the county's annual medical costs from $32 million to $4 million.

Changing political parties is a risky business, but less so for Lucas than for some. Not long ago a move from the Democratic to the Republican Party would have been perceived as going from something vaguely good to something narrow. Today the move can be portrayed, as Lucas pictures it, as emancipation from "special interests." Besides, today the parties are more ideologically differentiated than they once were, and Lucas' ideas clearly establish him as a Republican, and a rarity.

Most black leaders of the old civil rights groups now deny the principle that once animated those groups. It is the principle that race should be irrelevant to civic life and is inherently unacceptable as a basis for state action.

These leaders have a vested interest in expanding what has emerged in the name of affirmative action: a racial spoils system of hiring quotas, minority "set asides" and the rest. Such leaders denounce blacks who deviate from the old orthodoxy that government action is the key to improving the condition of blacks.

Blacks especially, but all other Americans, too, suffer from the shortage of black leaders, especially elected leaders who will say this: the principal impediment to the improvement of blacks' lives is not racism; and changes in the behavior of individuals can do more than changes in government policy.

Those two propositions are true, as is this: blacks in metropolitan ghettos face economic and cultural problems that would not be significantly less daunting were the blacks to become white.

Glenn C. Loury, a black professor at Harvard's Kennedy School, writes in The Public Interest that we live in the "post-civil rights" era. The principal challenge is the "internal problems which lower-class blacks now face." The problems are internal in the sense that they "involve at their core the values, attitudes and behaviors of individual blacks."

Nothing does more to perpetuate poverty than the disintegration of black families, and especially the conceiving of children out of wedlock. When two-thirds of the children born in a ghetto are illegitimate, that is a catastrophe that is not the fault of "society" and cannot be corrected by Congress.

Political discourse has been impoverished by a black leadership class reluctant to focus on the values, attitudes and behavior of individuals. Lucas, a devout Catholic who is abstemious about alcohol and immoderate only about work, is eager to change the focus. That is why he became a Republican, and why he may be a paradigm of the right politician for the post-civil rights era.