The Reagan administration, in the face of growing congressional opposition, called yesterday for continuing "most favored nation" trade benefits to Romania for another year but said the issue has become an agonizing "judgment call."

Assistant Secretary of State Rozanne L. Ridgway, testifying for the administration, said the question of U.S. trade benefits for Romania is "a tough call" because of "religious rights issues and the treatment of the Romanian people across a broad range of human-rights principles."

Chairman John C. Danforth (R-Mo.) of the Senate Finance subcommittee on international trade said developments in Romania have caused "a great burst of concern" in Congress and for the first time created "significant doubt" concerning whether the trade benefits will be continued. Separate bills have been introduced to revoke the trade benefits or to suspend them for six months.

Several members of Congress and representatives of human-rights organizations testified about religious and political repression in Romania, which along with Hungary is the only Soviet-bloc nation to have "most favored nation" trade status. Revocation or suspension of the benefits under authority of the 1974 Jackson-Vanik Amendment would "send the message" to Bucharest that increasingly serious abuses must be stopped, the subcommittee was told.

But Deputy Assistant Secretary of Commerce Franklin J. Vargo and representatives of several business groups defended the trade relationship with Romania on economic grounds. Vargo said Romania has become a "key market" for U.S. firms and that 5,000 U.S. jobs and $200 million in U.S. sales would be lost if the trade benefits are ended.

U.S. exports to Romania, which include power turbines and electrical equipment as well as agricultural commodities, would be stopped in retaliation if U.S. trade benefits were denied to Romanian imports, Vargo said. He and Ridgway testified that a six-month suspension of trade benefits would have nearly the same effect as a permanent revocation.

Romanian authorities demolished the Romanian Jewish community's only remaining Sephardic synagogue July 21 in connection with an urban renewal project despite repeated expressions of concern by the U.S. administration and Jewish groups and the governments of Israel and Spain, Ridgway said. A large Seventh-day Adventist Church is now threatened with demolition, she added.

At the same time, however, Romania has notified Washington since mid-April that 1,500 persons on U.S. lists have been approved for emigration. Ridgway said 154,000 Romanians have been permitted to leave for the United States, West Germany and Israel since 1975. She noted that freedom of emigration is the basis for political judgments regarding trade benefits under Jackson-Vanik, not the human-rights situation in general.

In an effort to bring about new moves from Bucharest, Danforth and 17 other senators sent a letter Tuesday to Romanian President Nicolae Ceausescu asking for a variety of steps that would have "major importance" in congressional consideration of the trade benefits.

The steps include importation and distribution of "a substantial number" of Romanian Protestant Bibles, accommodations with Romanian churches rather than demolition of them, confirmation that 15 named Romanians have been released from prison in amnesties, a clampdown on bribes and other payments in connection with emigration passports and permission for a particular family to emigrate to the United States.