Bill Keyes is soft-spoken, yet self-confident, a black conservative by choice, and bold enough to stand up in this town that voted overwhelmingly for Jimmy Carter and declare that, "Ronald Reagan and I agree on the issues."

Keyes' name is not a household word in Washington, although his cause -- trying to win voter approval of a proposal for an educational tax credit in the city -- is becoming an increasingly hot discussion item.

The proposed referendum is usually, and often inaccurately, associated with conservatives. To some, that would make it a sure bet to falter in this proverbially liberal town. But Keyes is the first to disagree.

The secret to his optimistic outlook can be found in his roots in Washington -- not this Washington, but Washington, N.C., a small Eastern Carolina town like those Tarheel hamlets that are the old country of so many blacks who live inthe backbone and bootstrap communities of the nation's capital.

"I hitchhiked here from Washington, N.C., four years ago with two suits, wearing sneakers and jeans, and with $5 in my pocket," said Keyes, the son of two public school teachers. A college dropout from East Carolina University with no connections to insiders' Washington, he landed a night job in the mail room of the Longworth House Office building, and volunteered his daytime hours on the staff of Rep. Dale E. Kildee (D-Mich.). Now he is an economist with the House-Senate Joint Economic Committee.

"I was just a guy who hustled here and succeeded because he had a goal," Keyes said.

Those plain Southern roots and the work ethic mentality give him common ground with many people here, Keyes claims. Here, there is similar settled middle-class black community steeped in bible-thumping, God-fearing church tradition.

"Washingtin is perceived by the whole world as being a very liberal place," Keyes said. "I don't think people here are all that liberal. People want crime to be controlled. People want the most that they can get from their taxes. There is a very, very strong moral and religious influence in this city, a very strong church influence. In many cases, the council goes against the wishes of that church-going community."

This is what Keyes, 27, is counting on to prove that he is right and that the city's elected leadership, many of whom are veterans of the civil rights movement and many of whom are opposed to the initiative, are wrong.

Keyes claims that it is middle-class black Washington that supports the initiative, because the hard-working residents of Northeast and Southeast Washington want the chance to be able to send their children to private schools.

But some persons say is is Keyes and his group who are out of step with the voters.

"Everybody I've talked to is against it," said Everett Scott, former president of the D.C. Federation of Civic Associations. "I'd like to know where they got those (27,000) signatures from (to place the question on the ballot)."

"It's going to impose a burden on the District of Columbia without any benefits," said Nelson C. Roots, president of the Pleasant Plains Civic Association in Northwest Washington.

This specific issue has already unified most of the city's leadership, including politicians, community group heads, civic association activists and others who have been spreading the common gospel that this initiative would bring untold havoc to the city government.

But Keyes is undaunted. He said he is hoping the initiative can make it past the legal hurdles to wina spot on the ballots, where he said his side can fare best in a true debate over the issue.

Said Keyes, in his usual measured self-confidence, 27,000 Washingtonians can't be wrong.