When the Congressional Black Caucus offered its 1988 budget alternative on the House floor last April, Rep. William H. Gray III (D-Pa.), chairman of the Budget Committee and a caucus superstar, did not support the measure -- he just voted "present."

The North Philadelphia Democrat, who once helped draft the caucus' liberal-progressive alternative to Reagan administration cutbacks, now must craft the kind of consensus-minded budget plans that will win the allegiance of a broad spectrum of House Democrats.

"It's not an issue of {being} black," said Gray, who has voted "present" on every Democratic alternative since becoming chairman in 1985. "The issue is: I'm chairman of the Budget Committee, a Democrat. I build a consensus. I walk out with a budget. Now, do I vote against my own budget? . . . That doesn't make a lot of sense."

"It's not a problem of race," he said. "It's a problem of what happens to any member of Congress who gets elevated to a position of leadership."

Not everyone in the 23-member caucus agrees with Gray's premise, and therein lies a predicament for Gray and other blacks who rose through the seniority system to top committee posts and now are torn between their allegiance to the caucus and their responsibilities as Democratic leaders.

Rep. John Conyers Jr. (D-Mich.) said he and other black members "take exception" to Gray's refusal to endorse the caucus alternative as a symbolic show of solidarity. "I draw the line where he {Gray} ac- tively campaigned against the black caucus resolution," Conyers said.

For the caucus, which begins its 17th annual legislative meeting today at the Washington Hilton, the dispute illustrates one of the tensions within an organization that is now operating at a new level of political sophistication.

It has grown from a high-profile alliance of relatively young, low-ranked members to one of the most effective caucuses on Capitol Hill, as it demonstrated last year in pushing through economic sanctions against South Africa and winning approval for billions in federal contracts set aside for minority companies.

Yet, as its members gain in seniority and power, the caucus itself has become a less important playing field for promoting a black agenda.

"The caucus is not the only arena where black members can express their views now," said George A. Dalley, counsel and staff director to Rep. Charles B. Rangel (D-N.Y.). "Therefore, in some ways the caucus is diminished in its visibility . . . . The sum of its parts is greater than the whole."

Black politicians are now playing the game much like their white colleagues, angling to move up in the ranks of the House leadership and building broad-based coalitions around specific bills.

"Clearly, in the past the caucus has defined itself as a group outside the political structure, offering pure proposals, pushing for change," said Norman J. Ornstein, a congression- al scholar with the American Enterprise Institute. "But as you have people moving up to real policy power . . . to a degree you will get a redefinition of the role of the caucus."

The caucus boasts an impressive roll call: Five members are chairmen of standing committees, two head select committees, and 18 head subcommittees.

"This is a very influential group, forgetting about the fact that they're black members," said House Majority Leader Thomas S. Foley (D-Wash.). "If you have any group of these members linked together, they would be an extremely influential group."

Rep. Augustus F. Hawkins (D-Calif.), a senior caucus member and an author of the Humphrey-Hawkins Full Employment Act, is chairman of the Committee on Education and Labor. Rep. Louis Stokes (D-Ohio) is chairman of the Permanent Select Committee on Intelligence and also serves on the Iran-contra committee. Rep. Julian C. Dixon (D-Calif.) is chairman of the Committee on Standards of Official Conduct, which passes judgment on House members.

Rep. Mickey Leland (D-Tex.) heads the Select Commitee on Hunger. Rep. Ronald Dellums, chairman of the District of Columbia Committee, also heads an Armed Services subcommittee that can open or close military installations. Rangel, chairman of the Select Committee on Narcotics Abuse and Control, is also the fourth ranking member of the Ways and Means Committee.

Once, southerners from safe districts flourished in Congress under the seniority system, gradually taking control of practically every important committee and using that power to their region's advantage. Now, veteran black House members with solid political bases have accomplished the same thing, moving into key leadership roles and wielding extraordinary power.

"When I first came to Congress, I was opposed to the seniority system," said Del. Walter E. Fauntroy (D-D.C.), the fourth-ranking member of the Banking Committee. "The longer I'm here, the better I like it."

Dellums, the only black on the Armed Services Committee, opposed the successful move by Rep. Les Aspin (D-Wis.) in 1984 to oust Rep. Melvin Price (D-Ill.) as committee chairman.

Like most of his colleagues in the black caucus, Dellums supports the seniority system that protects his position.

Stokes, a founding member of the caucus, said the group had grown in stature and influence as individual members have moved up the seniority ladder. "I don't think we've forgotten our roots," he said. Still, most members "are sophisticated enough" to differentiate between allegiance to the caucus and their responsibilities as Democratic congressional leaders, he said.

"We're not considered as black chairmen," he said. "We're chairmen of committees of this Congress."

As it has grown in influence and diversity, the caucus' internal politics have become more contentious. Foreign aid and the budget are among the most hotly debated issues, according to some members and sources close to the group.

Many of the members are angered that vast amounts are spent annually on aid to Israel and Egypt, while the administration has sought to reduce aid to African, Caribbean and other Third World nations. And while a majority of the caucus favors continued high levels of sup- port to Israel, many are disturbed by the Israelis' close relations with the South African government.

"Next to the Jewish members of Congress, no group supports Israel as strongly as the black caucus -- even those like me," said Dymally, who has been critical of U.S. policy in the Mideast. ". . . The only troubling issue is Israel's relationship with South Africa."

Freshman Rep. John Lewis (D-Ga.), a prominent Atlanta civil rights leader, is among Israel's staunchest supporters within the caucus -- a position that occasionally has put him at odds with other members.

"As our closest ally in the region, we must do what we can to protect Israel," Lewis said last week, after returning from an eight-day official visit to Israel.

The origins of the historical trend that produced the black caucus can be traced to 1942, when the election of the late representative William L. Dawson (D-Ill.) began a flow of big-city black Democrats to Congress. Thirty-eight blacks have followed him, including four elected last year -- Reps. Mike Espy (D-Miss.), the first black elected to Congress from Mississippi since Reconstruction; Kweisi Mfume (D-Md.), treasurer of the caucus, Floyd Flake (D-N.Y.) and Lewis.

Most of the senior members of the caucus who hold top committee assignments were first elected to Congress between 1962 and 1970.

Caucus members gained overnight national attention in 1971 by boycotting President Nixon's State of the Union address to protest the president's refusal to meet with them. Nixon later agreed to a meeting, and caucus members presented him with a list of 60 recommendations for government action.

The caucus scored a major breakthrough in the mid-1970s by persuading the House leadership to put blacks on the Rules, Appropriations and Ways and Means committees. Former representative Parren Mitchell (D-Md.), the past chairman of the Small Business Committee, pioneered legislation giving minority businessmen access to federal government contracts.

In 1976, the caucus created a tax-exempt foundation to conduct educational and social policy research. TransAfrica, the group headed by Randall Robinson that mobilized the lobbying effort in support of South African sanctions, is an offshoot of the caucus.

Gray, 45, a minister and former history professor, was first elected to the House in 1978. He landed an assignment on the Budget Committee in his second term, and by 1984 he had begun his campaign to become chairman.

Since becoming chairman, Gray said, he has encouraged the caucus to continue to propose budget alternatives but has routinely voted "present" when they and other Democratic alternatives have been voted upon. In pushing through his own budget plans, Gray said, he has achieved many of the goals of the caucus.

"I'm not here to do the bidding of somebody just because they happen to be black," he said. "If I agree with you, I agree with you. I set my policy. I think it's a fair policy, but that policy has nothing to do with being black. It has to do with the position I have institutionally as chairman of the Budget Committee."