Delegates to the Democratic midterm convention gave an enthusiastic "thumbs up" approval yesterday of a resolution calling for ratification of the amendment giving District of Columbia residents voting representation in Congress.

Delegates from Kansas, South Carolina and Michign joined with those from the District in urging all Americans, in the words of D.c. d/el. Walter E. Fauntroy, "to rise above race, region and party to correct an historic wrong" by ratifying the amendment.

HUD Secretary Patricia Roberts Harris told the convention that she has been a D.C. resident more than two decades. "As a cabinet member I can talk and work with senators and congressmen, but I cannot vote for any of them," she said.

After six brief speeches, and no opposition, party chairman John C. White chose to forgo the traditional voice vote in favor of the thumbs-up gesture as a way for the 2,500 delegates and alternates to register their approval of the proposal.

Approval of the resolution was no surprise, because the issue has been official party policy since its inclusion in the 1976 platform. But when it passed, Mary Eva Candon, an alternate in the D.C. delegation, cheered, "We did it, we won."

Perhaps more important to the cause were signed commitments to work for ratification obtained by members of the D.C. delegation for hundreds of party activists throughout the country.

Fauntroy said the spadework done here by the 22-member delegation can serve as "an instructive example" to other District residents on how to line up support at national conventions of all kinds of organizations.

D.C. Democratic chairman Bob Washington said approval of the resolution, along with President Carter's mention of the issue in a speech here Freiday, will help publicize the amendment, which is not widely known or discussed in many parts of the country.

The amendment has been ratified by two states, New Jersey and Ohio, since its passage by the Senate last August. Michigan party chairman Morley Winograd told the delegates that his state will be the third, prediction passate within the next few days. He challenged other states to "follow Michigan's ead."

Rep. Mendel J. Davis of South Carolina sais he worked for passage of the amendment in the House and now he will work for its ratification in his home state legislature.

Gov.-elect John W. Carlin of Kansas told the convention "What's right is right." Carlin, who has been speaker of the Kansas House, said later that the strong support of Sen. Bob Dole (R.-Kan.) "ought to tell the people of Kansas that this is not a partisan issue."

Fauntroy told the convention that "this resolution places before the American people a moral question." He said of 115 countries that have capital cities or federal districts, only two military dictatorships and the United States "deny voting representation in their national legislatures to residents of their capital cities."

In an emotional ending that he employs repeatedly as he stumps around the country on behalf of ratification, Fauntroy said that "cowardice asks the question is it safe, vanity asks the question is it popular, expediency asks the question is it politic, but conscience asks the question, is it right?"

He then urged the delegates to "make a commitment" to the D.C. amendment, "not because it is safe or popular or politic, but because your conscience tells you it is right."