Supporters of the proposed D.C. voting rights amendment to the Constitution, who last fall tried to rush the proposal through several legislatures, are now urging backers to proceed cautiously, fearing that defeat in one or more states could have a snowballing effect.

"Go slow" is the word being sent to legislative supporters in Maryland, New York, Wisconsin, Missouri, South Carolina and North Dakota, where ratification is headed for critical votes this month.

In hopes of delaying what appears to be certain defeat in North Dakota, D.C. Del. Walter E. Fauntroy yesterday dispatched one of his top aides to Bismarck, the capital.

"The issue is being considered without information being available to the degree we'd like," said Elena Hess of Self-Determination for D.C., the umbrella group that is directing the nationwide ratification drive.

Hess conceded that the new stance is "absolutely" the reverse of the position taken last year, when supporters introduced ratification resolutions in the California and Delaware legislatures within a week of the amendment's passage by the U.S. Senate last August.

At that time, opponents of ratification urged delay until more information could be presented to the general public. California postponed action and Delaware and Pennsylvania rejucted ratification, at least temporarily.

Three states, New Jersey, Ohio and Michigan, have ratified the amendment, which would gove the District of Columbia two senators and one or two members in the House. For the amendment to take effect, 38 legislatures must ratify it within seven years of last summer's approval by Congress.

The trip to Bismarck yesterday by Johnny Barnes, Fauntroy's legislative assistant, was prompted by the belief that "we are going to get killed up there" when a vote is taken, according to Richard W. Clark, the Common Cause lobbyist who is executive director of the coalition.

"Our brochure (outlining reasons to vote for ratification) is at the designer," Hess said. "We'd like it to be in the hands of every legislator before a vote is taken. Our message is 'go slow,' even in easy states such as New York."

Supporters in Maryland will meet Thursday in Annapolis to map strategy for a hearing scheduled before the Senate committee next week.

Maryland is one of the states where the outcome is viewed as uncertain.

Tracking progress of the amendment is a dizzying task. Volunteers in the Common Cause headquarters here have been making daily calls to the more than two dozen states whose legislatures are now in session.

"We can call one day and be told nothing is happening, and the next day find out a committee is set to vote," Hess said.

For example, no one connected with the ratification drive was aware until late last night that the judiciary committee of the South Carolina House of Representatives had approved the amendment yesterday.

North Dakota State Sen. Ernest Sands (R-Velva) said last night that his judiciary committee will vote to-Day on ratification.

"We delayed for a week because Congressman Fauntroy said he wanted to testify, but he sent his assistant," Sands said.

The New York legislature took the first step toward ratification yesterday when the state Assembly's judiciary committee, by a vote of 13 to 8, passed the resolution.