The Reagan administration and members of Congress in both parties, seeking to break the apparent policy deadlock over Nicaragua, are considering new approaches, including "humanitarian aid" to the rebels' families and expanded economic sanctions.

Both sides agree that the Democrats appear to have blocked further covert military aid through the Central Intelligence Agency to rebels fighting the leftist Sandinista government in Nicaragua. But the Democrats, no less than the Republicans, want to maintain pressure for political change there and are casting about for alternatives that can win public support.

Many Democrats are uneasy about recent developments that appear to indicate growing political and economic repression in Nicaragua. They want to help stop that trend but have not found a coherent alternative policy.

Administration officials fear that the rebel aid program is dead but continue to push for it -- in various forms -- because they have made it their policy keystone and have no backup positions.

The latest idea from the administration would replace the nominally covert program of aid to the rebels, called "contras," with overt humanitarian aid to families of the rebel fighters and to Nicaraguan refugees living in Honduras, according to Senate Republican sources.

The assistance would total about $14 million, the same amount the administration earmarked for the contras, in hopes that it can win a congressional vote scheduled for March.

This approach would bow to the insistence by some key Republicans, including Senate Select Committee on Intelligence Chairman David F. Durenberger (R-Minn.), that any rebel aid program be legal. The law forbids efforts to overthrow governments with which the United States has diplomatic relations, and the contras have made it clear that their objective is to oust the Sandinistas.

Humanitarian funding for rebel associates was discussed briefly during the prolonged wrangle in Congress over Central America policy last year and was dropped as too obvious a subterfuge.

"Essentially it would be an ESF Economic Support Fund account for the contras," a way to put aid within their reach if not directly in their hands, a key Republican staff member said.

A high State Department official discounted the idea. "We aren't going to try to play games with Congress," he said. "We're still considering a whole range of options." Then he asked, "Do you have any ideas?"

Other approaches under discussion include a new sales pitch, which Reagan used Thursday, that funding the contras is self-defense under the United Nations and Organization of American States charters that provide for "individual and collective security."

Republicans also are considering some kind of expanded economic sanctions, possibly including pressure on U.S. allies to halt all trade with Nicaragua. A leader of Nicaragua's domestic opposition, former Central Bank president and ambassador Arturo Cruz, recently voiced opposition to such sanctions as too damaging to Nicaraguan civilians.

Several Democrats pointed out that previous U.S. efforts to organize international boycotts against Cuba and the Soviet Union had very limited success.

In developments that impressed many members of Congress as signaling serious erosion of rights in Nicaragua, Cruz came out in favor of more funds for the armed contras, and opposition publisher Pedro Joaquin Chamorro announced he was going into self-imposed exile in Costa Rica until conditions improve in Nicaragua. Several Democrats cited recently published reports of widespread forced army recruitment and black marketeering in Nicaragua as further evidence of repression.

"The Sandinistas haven't done anything recently that would increase anybody's confidence in them," said Rep. David R. Obey (D-Wis.), who is expected to be named chairman of the Appropriations subcommittee on foreign operations this week. "There is something to be said for keeping the Sandinistas under pressure or in doubt as to our intentions . . . but our involvement with the contras tends to make the gringos Americans the point at issue, rather than the shortcomings of the Sandinistas."

The Democrats acknowledge that they have come up with few alternatives but contend that they retain a firm House majority against the contra operation.

"I continue to struggle with trying to find a compromise that could achieve the ends the administration wants to achieve, while getting us out of this contra program," said Rep. Michael D. Barnes (D-Md.), chairman of the Foreign Affairs subcommittee on the Western Hemisphere.

One idea, he said, would emphasize international treaties and organizations as forums for neighboring countries to complain about Nicaraguan interference and thus bring worldwide pressure on the Sandinistas to change their ways.

Nicaraguan Ambassador Carlos Tunnermann acknowledged in an interview that some Democrats perceive a worsening situation in his country. "That perception is not correct," he said. President Daniel Ortega promised a broad amnesty program, continued mixed economy and political pluralism in a recent speech, and reports of draft resistance and monetary speculation are isolated cases, he said.

Tunnermann noted that Cruz had visited Nicaragua without incident two days after calling for renewed contra funding and that it was Reagan who halted bilateral talks with Nicaragua and refused to let the World Court rule on his policies. Tunnermann repeated charges that the contras are guilty of atrocities and human rights violations.

Rep. William V. (Bill) Alexander Jr. (D-Ark.) last week suggested a party policy that would increase support for ongoing Contadora regional peace talks and also call for a hemispheric peace conference to which Cuba would be invited.