PRESIDENT REAGAN'S powerful counselor Edwin Meese III has said it would be demeaning to name a black wihin the Reagan White House to hold the traditional job of liaison with civil rights organizations and other blacks interest groups.

That may be a noble opinion. But the political reality is that the highest ranking black in Reagan's administration already plays that role, whether he holds the title or not.

Melvin Bradley, 42, White House adviser on domestic policy, is one of 351 people on the White House staff -- and one of a half dozen senior policy advisers to chief domestic policy adviser Martin Anderson, who reports directly to Meese, who then reports to the president. Bradley is not exactly in the inner circle of power.

But because he is black Bradley probably has greater access to Meese and Ronald Reagan than others at his level, although, criously, he seems reluctant to use it. "The power is laying around, and he won't pick it up," said Toye Lewis, Bradley's executive assistant.

But despite Meese's belief -- "You're not going to have one person that all blacks have to funnel through. I think that is demeaning" -- Mel Bradley is that funnel right now. He is an official policy adviser and an unofficial conduit for constituent problems peculiar to blacks. "So far. "I've been trying to handle it both ways," he said, "but I don't know how much longer I can . . . take the time and staff . . . there is a conflict. . . . "

Along with a small group of other reporters, I met recently with Bradley to try to meadure his influence. Bradley seemed unable or unwilling to tell us anything he has done that has made much of a difference. He recommends urban affiars policy to the president but when pressed to be specific, he vaguely mentioned the Small Business Administration minority set-aside program. He said he didn't think it proper to say more. If Bradley is helping make policy, it is hard to see where.

Now it's clear that most blacks didn't vote for Ronald Reagan and the president does not have to feel he owes them much, but it is strange that in this crucial time the most visible black on the White House staff is reluctant to talk about his goals and accomplishments. He says urban policy is his first love and interest, but when you ask him about possible social unrest in the wake of the budget cuts, he says that he does not expect "all those things to happen."

On the one hand, Bradley seems a competent person who is out of place at the level of the hardball political games played in Washington. On the other hand, he does seem to follow in the tradition of black Republicans with their conservative ideas. But the potent isues of today need a strong, hard-driving intelligence.

With the cities in some cases powder kegs of high unemployment, budget-pinched schools and economic hard times, niceness somehow seems out of place. The need today is to convey to the Oval Office the problems and aspirations of frustrated black people and the depth and reality of the dilemmas they face.

Power in Washington is measured by proximity and accessbility. Insider blacks who have occupied the traditional liaison position -- Louis Martin under Jimmy Carter and Hobart Taylor under Lyndon Johnson -- at least had offices within the White House. Bradley works next door in the Executive Office Building.

Bradley says he doesn't want to stand apart from other senior policy advisers. "I don't want to be treated special," he said "i just want to be treated equitably."

A long-time political operative here said of Bradley, "It will take him six to nine months to understand the political landscape . . . to become acquainted with the way politics here work." Blacks simply don't have that much time to wait.

At a recent reception honoring Bradley and two other blacks in the administration, one guest described him as seeming "awed" by Washington. But to achieve political clout in this city of bald power, one needs a clear role, a sure way to help a constituency and a staff to get things done.Bradley seems to have not enough of any of these.

"He performed well for the black community in California," said Lewis, his assistant, "and I expect the same kind of performance from him here."

It could be that Melvin Bradley is a political sleeper, a man who wields power without making noise, although those are rare animals in Washington -- as rare as a sleeper in the Kentucky Derby.

But right now, it seems more likely that Mel Bradley is most of all a nice guy. And maybe that is exactly the kind of person with whom Ronald Reagan feels most comfortable as his closest black adviser.