Representatives of blacks and Hispanic-Americas, anxious to become more visible in President Carter's subcabinet than they are in his Cabinet, are stepping up their pressure on top administration officials.

Carter is scheduled to meet this afternoon with a delegation from El Congreso, the National Congress of Hispanic-American Citizens, which is upset that only two Hispanic-Americans have been appointed so far to high-level, policy-making jobs.

The Congressional Bank Caucus met with three members of Carter's Cabinet so far this week, and plans more meetings next week, in an effort to win not just more high-level jobs for blacks but also some commitments on issues.

The White House has not said publicly how far along the process of nominating subcabinet officials is. Few such nominations have been sent to the Senate, where many must be confirmed. But sources have said some Cabinet members have almost completed their selections.

Jack H. Watson Jr., a special assistant to Carter, said Monday that delays in announcing the appointments are the result of slow clearances by the FBI.

Carter sent a Mailgram Jan. 8 to his Cabinet appointees asking them to "recruit and place Hispanics who want to serve in his administration." The Mailgram mentioned three members of the Carter transition team who were "ready to assist you with affirmative action in his effort."

One of those members, Hank Lacayo, who heads the political arm of the United Auto Workers, said in a telephone interview from Detroit yesterday, "I do feel there's been a breakdown what he said and what has been done by staff of whoever."

Manuel D. Fierro, president of El Congreso hinted yesterday that his group's strong opposition to Terence Todman, the black U.S. ambassador to Costa Rica nominated to be assistant secretary of state for inter-American affairs, might be a bargaining chip during the meeting with Carter.

"We'd certainly be receptive to a proposal that would give us a Mexican-American ambassador to Mexico," Fierro said. "I think that will certainly be a factor in our continued opposition to Todman."

Members of the Congressional Black Caucus met Tuesday with Patricia Roberts Harris, Secretary of Housing and Urban Development, and yesterday with Agriculture Secretary Bob Bergland and Interior Secretary Cecil D. Andrus.

The caucus chairman, Rep. Parren Mitchell (D-Md.), said there would be "nothing definitive" said about the meetings until all of them had been held. But he called all three "excellent," and said he personally was "encouraged by some of the things I see in formation . . . almost across the board."

An aide to Andrus said the secretary "made a commitment to President Carter that he would . . . have the best affirmative action plan of all the departments."

"A number" of Andrus' appointments have been sent to the White House, but are caught in the backlog of FBI checks and Internal Revenue Service checks, the aide said. He refused to say what proportion were minorities or women.

Watson, Carter's Cabinet secretary, said the President has opened both of his regular Cabinet meetings by emphasizing "his expectation for all of the Cabinet members to exercise aggressive affirmative action efforts for women, for blacks, for Hispanics, for Asian-Americans, for native Americans and for other minority groups."

Fierro met with Attorney General Griffin B. Bell yesterday and said afterwards he thought Bell will "move in the next week or so to appoint some Latinos over there . . . He assured me he would do that."

The two Hispanic-Americans named to high-level positions so far are Arabella Martinez, designated as assistant secretary for human development in HEW, and Joe Aragon, who is acting director of the Community Services Agency is the Carter-administration's highest ranking Mexican-American.

In addition, Fierro said, El Congreso feels Alex Mercure will be named as assistant secretary of agriculture.