Washington — President Reagan has called for bipartisanship on foreign policy and rapped Congress for failing to back him in dealing with other nations. But this week his foreign policies are again under heavy attack on Capitol Hill. And the only bipartisanship is a union of Senate Republicans with Democrats against the United States role in mining Nicaraguan harbors.
A combination of dismay over the mining, anger over the limited consultation with Congress, and political tensions produced the lopsided 84-12 vote in the Senate to oppose spending money to float bombs in the waters of the leftist Central American country. Only 11 Republicans and one Democrat sided with the administration.
Critics charge that laying mines is a lawless act of war. It's a ''stake being driven into the heart of international law,'' says Rep. Jim Leach of Iowa, probably the most outspoken Republican opponent in the House.
Only hours after the Senate rebuked the President, Assistant Secretary of State Kenneth Dam returned to Capitol Hill Wednesday to defend the mining in Nicaragua as ''collective self-defense'' without formally confirming the US part in the so-called secret action.
''Is the mining of harbors an act of war?'' asked Rep. Michael D. Barnes (D) of Maryland, chairman of the House subcommittee on Latin American affairs.
''I don't believe that that is a correct statement,'' responded Mr. Dam, who said that the ''legal issue and the political issue has to do with what is unlawful use of force under the United Nations charter.''
Moreover, he defended the Reagan administration's efforts to withdraw jurisdiction from the International Court of Justice for two years in cases dealing with Central America.
A Nicaraguan complaint filed in that court might interfere with peace efforts of the four Contadora countries of the region, Dam said.
Such explanations are unlikely to satisfy many of the Reagan critics, who are speaking out with increasing stridency.
Sen. Edward M. Kennedy (D) of Massachusetts had stood almost alone in the Senate a week ago as he tried and failed to pass a series of amendments challenging the President's Central America policy.
But once news of US involvement in mining surfaced, his motion to express a ''sense of the Senate'' resolution against the mining sailed through the Senate.
''It's the first step,'' Senator Kennedy said after his victory.
But such optimism is still only speculative in Congress, which is cautious in foreign affairs issues. The Senate vote is nonbinding, and it does not necessarily promise a trend.
A top Republican aide called the vote an ''isolated incident'' that resulted from ''building up a head of steam'' because the members felt they had not been fully informed about the mining operation and yet were asked to support the Reagan policies.
The greatest volume of steam appeared to have built up in the office of Sen. Barry Goldwater (R) of Arizona, the venerable dean of conservatives and chairman of the Senate Intelligence Committee. Senator Goldwater fired off a fiery letter to William Casey, director of the Central Intelligence Agency, complaining that he had been left in the dark.
During a briefing hastily assembled with the CIA chief for senators, only ''one or two said they had been advised'' of the mining, reported Sen. James Sasser (D) of Tennessee. ''The audience was generally hostile,'' he said.
Ironically, the Democatic-controlled House Intelligence Committee had been briefed on the harbor mine operation weeks ago.
The question now is whether the Reagan administration can soothe the ruffled feathers and rebuild support within its own party for Central America policies. And for critics, the question is whether they can create enough pressure to force Mr. Reagan to change those policies.
Asked about shutting down the US aid to rebels in Nicaragua, House Speaker Thomas P. O'Neill Jr. (D) of Massachusetts said Wednesday, ''I certainly would love to if we possibly can,'' but made no predictions. He added that the CIA has enough money to continue the anti-Sandinista activity in Nicaragua through May.
The speaker also said that the administration's request for an additional $21 million for covert activities in Nicaragua ''hasn't got a chance.''
Meanwhile, opponents will also continue to challenge the Reagan limitations on the International Court of Justice. Senate minority leader Robert C. Byrd (D) of West Virginia criticized the Reagan administration for saying it will ''disregard any claim of jurisdiction by the court for two years, when we want other countries to live up to and abide by international law.''
Sen. Daniel Patrick Moynihan (D) of New York, speaking on the Senate floor, produced a 1946 Senate Foreign Relations Committee report from 1946 on the world court which requires the United States to give six months' notice of termination before withdrawing jurisdiction ''in the face of a threatened legal proceeding.''