Mayor Marion Barry, in an effort to breathe new life into the stalled campaign to win passage of the D.C. voting rights amendment, urged leaders of Washington's business establishment yesterday to give greater political and financial support to the amendment drive.

"This is a very critical period in the campaign," Barry said, speaking to about 150 at a fund-raising breakfast for the amendment put on by the mayor's office.

Barry said the approval of 28 more state legislatures is needed to ratify the amendment, which would give the District two senators and at least one voting member in the House, and the deadline is less than three years away.

The mayor drew laughter when he told the audience that in an earlier meeting with Israeli President Yitzhak Navon, when Navon asked how the District's efforts at increased self-determination were faring, "I said not as well as self-determination for Israel."

Momentum for the amendment has dropped off sharply since Congress passed it in 1978. Of the 10 states that have ratified it, seven did so in 1979, two in 1980, one in 1981 and none last year.

Supporters of the amendment said local business leaders are an obvious source of badly needed campaign funds, and they have the influence to counter opponents' efforts to focus on the District's liberal political image.

"The key to success is the people in this room, the business community of the District of Columbia," said Del. Walter E. Fauntroy, who, as the District's nonvoting member of Congress, has been a chief sponsor of the amendment.

Richard Clark, chairman of a coalition lobbying for the amendment, said the group, whose three-person full-time staff is now working without pay, turned in desperation to Barry last month to organize the fund-raising breakfast.

Those present included leading businessmen, lawyers and officeholders, including Thomas J. Owen, president of The Greater Washington Board of Trade, and Edwin K. Hoffman, chairman of the board of Woodward & Lothrop, City Council Chairman David A. Clarke, four other council members and city administrator Elijah B. Rogers. Between $15,000 and $16,000 was raised at the breakfast, organizers said.

Clark said that in addition to lobbying for the amendment's ratification, the campaign is an important tool for educating the rest of the country about Washington's needs, including issues such as elimination of congressional oversight over the District's laws and budget. "Even if we don't win on the amendment, this process is very vital," said Clark, who was recently named executive assistant to new council President Clarke.

Board of Trade President Owen said in an interview after the breakfast that efforts to rally the business community behind the amendment campaign are in part being hampered by confusion stemming from the separate campaign to win statehood for the District. He said the board of trade has supported the voting rights amendment, but there is "no question" the board has "difficulties" with the proposed statehood constitution, which has been criticized as being too liberal.

However, both Barry and Clarke said they have decided to push simultaneously for adoption of the amendment and statehood. "I don't see any conflict," Barry told a reporter. He said both issues help focus attention on the need for more District self-government.

An aide to Fauntroy said that while the delegate was initially lukewarm to the statehood effort, he is now planning to lobby actively for it in Congress.