As proponents tried to buy time to win additional support, the Equal Rights Amendment faced defeat today in the North Carolina General Assembly.

Chances for ERA ratification appeared slim following the announcement by Sen. Joseph E. Thomas of New Bern that he would vote against the amendment.By most nose counts, Thomas became the 26th legislator, a majority in the 50-member senate, to declare himself against ERA.

ERA supporters attempted to delay a vote on ratification for at least a week, but opponents pulled off a parlimentary maneuver that may force a roll-call vote as early as Friday.

The North Carolina Legislature has three times in the past six years turned down ratification of the proposed amendment to prohibit discrimination on account of sex. ERA proponents this year sought to emphasize traditional political tactics and to depict ERA as a mainstream, middle-of-the-road issue.

Nevertheless, their tactics have so far fallen short, in the face of intense activism by ERA opponents, many of them members of the fundamentalist churches. At a public hearing Tuesday, busloads of opponents, including hundreds of students at Christian academies, showed up to pray at the entrance of the Legislative Building.

In addition, former U.S. senator Sam J. Ervin Jr. (D-N.C.) appeared at the hearing, saying that ERA "is destructive of the system of government our Constitution was designed to provide for."

Before reaching a decision, Thomas was the target of both sides' lobbying tactics. Thomas, the president of a Weyerhaeuser Co. subsidiary who represents three coastal counties, was appointed to the legislature last month by Gov. James B. Hunt Jr. following the death of a senator who had earlier voted for ERA.

Thomas talked to the governor, and was telephoned Sunday evening at his home by President Carter, both of whom asked the legislator to support ERA. Hunt's wife, Carolyn, was the chief witness at the public hearing for ERA proponents.

However, Thomas carried in his pocket a tally of letters and telegrams from residents of his district -- 1,094 for ERA, 2,765 against. "I'm going to vote the sentiment of my district," he said. "They don't want federal intervention."

Jessie Rae Scott, the principal pro-ERA lobbyist and wife of former governor Bob Scott, said that amendment proponents will continue trying to find new support.

To gain extra time, supporters of the amendment on the Senate constitutional amendment committee voted to delay consideration for a week.

However, Sen. Julian Allsbrook of Roanoke Rapids, an ERA foe who is chairman of a separate Senate judiciary committee, tried to bring ERA to the floor by attaching ratification legislation to another bill. Allsbrook's maneuver may compel the Senate to vote late this week.

One option that has been under consideration by ERA proponents is to defer ERA ratification until 1980. Under North Carolina legislative rule, if ERA is defeated this year, it cannot be brought up again next year without a difficult suspension of the rules.