When Stevie Wonder conducted a press conference in Washington yesterday, he was barraged with questions about human rights, the country's conservative trends, civil rights, the recent killings of black men in Buffalo and whether Ronald Reagan is a racist.

The reason Wonder the entertainer was probed on these issues was because he has become a respected interpreter of some of those social issues. And yesterday, here he was in a darkened room of the National Press Club, announcing a march on Jan. 15 to call for a holiday in honor of Rev. Martin Luther King Jr. Though his songs are much tighter than his press conferences, the blending of the man and his politics remains as clear, delivered with the same slightly heady musings.

Wonder, who was dressed casually in brown slacks, a white knit sweater, and had his shoulder-length hair braided with intricate red, yellow and brown beads, barely mentioned his concert at the Capital Centre tonight. Yet he insisted he has not become a lobbyist. "I am not a politican. I am an artist. I do express certain feelings about certain things. Even if I give a song that deals with a negative subject, it's only constructive critism to encourage our minds to look and go in a positive direction," said Wonder, his voice low and slow with thought. "I want to encourage those of you who are communicators -- and that's what I am -- to deal with how we can offset that cancer that's killing many minds with negativity, to look in the direction of what is going to unify us as human beings."

Wonder sees this confluence of singer and politician as a necessary, and natural, extension of his own life experiences. "I feel comfortable answering any question I know something about.Music is the form which God saw significant for me to use as my vehicle of expression. It does not mean I should not deal with other things. As a matter of fact, in some of our songs we talk about very political things. They are not so much political, as about basic rights every human being should have. A person should not go through a trip to get into a house."

In is latest album, "Hotter Than July," Wonder skillfully interplays the traditional pillow ballad with the political insight that has marked his music in the last four years. On the album is a song about the need to celebrate King's birthday, a reggaeinspired piece that includes a celebratory line about the independence of Zimbabwe, and a lament about housing discrimination, "Cash in Your Face."

His success and his age -- now a seasoned 30 -- have given him the impetus for this expression. "I guess I feel more and more about what is happening. It started, not with my writing, but the writings of Bob Dylan, when he did 'Blownin in the Wind.' I felt that, I experienced that kind of racism when I was little. I wanted to go to a bathroom in the gas station, and said 'where's the bathroom' and the guy said 'way in the back.' And there was nothing in the back," he recalls. "Even if I did not experience it personally, I have the sensitivity in hand to feel what people are going through."

The message-music of folk-blues master Leadbelly, regge and Bob Marley and songs like Ray Steven's "Everything Is Beautiful," says Wonder, "is a reaching out to the belief that people really can come together."

A true incident prompted his song on the housing double-standard. Keith Harris, a black administrator of one of Wonder's companies, was turned down for an apartment in Los Angeles after they had told his white girlfriend an apartment was available. "I had the track down, and the lyrics just came to me in the middle of the night . . . It was stimulated by Keith's experience. mIt's ridiculous, this kind of thing happens every day."

In the 13 concerts he has done so far in this tour, says Wonder, he has spoken about the King holiday effort. By the end of the tour he will have reached a quarter-million people. Wonder says he is pessimistic about the outcome of that bill, which has been introduced in every Congress since 1969.

One thing they can't do, says Wonder, is stop the music. "Music has lasted through conservation periods, through liberal governments. It's going to go on, since the song of the bird, since the drum of Africa. It's something they can't stop, people expressing themselves."