WHEN President Harry Truman looked down Pennsylvania Avenue toward a Congress dominated by Republicans, he saw a ray of light: an opposition lawmaker ready and willing to support the administration's landmark foreign policy initiatives.
The legendary cooperation between the Democratic president and the GOP chairman of the Senate Foreign Relations Committee, Arthur Vandenberg, produced a golden age of bipartisanship. ``There has to be cooperation under such circumstances or America would be devoid of any foreign policy at all,'' the Michigan Republican wrote in 1951.
When President Clinton looks down Pennsylvania Avenue, he sees only darkness. No Republican will seek to play Senator Vandenberg's role in the new Congress, political analysts predict, in the absence of any overarching threat to American interests abroad.
``If bipartisanship were to be duplicated now it would not be in the area of foreign policy,'' says Harvard University historian Ernest May. ``What made it work during the Truman administration was a shared sense of peril and the need for unity in the face of the Soviet threat.''
As one of the leading Senate isolationists before World War II, Vandenberg seemed an unlikely candidate to play the role of conciliator after the war. But the Japanese attack on Pearl Harbor in December 1941 convinced him that the US could no longer remain separate from the world.
Thereafter, he led his party to support the United Nations, the Marshall Plan for the reconstruction of postwar Europe, and NATO. He was convinced that America could only speak with power if it spoke with unity.
During the Truman administration, Vandenberg worked intimately with senior US diplomats.
``We couldn't have gotten much closer together unless I sat in Vandenberg's lap or he sat in mine,'' Truman Secretary of State George Marshall later recalled.
Since the end of the Truman administration no one has been able to play Vandenberg's role, and there are no obvious takers in the new Republican Congress.
Vandenberg's current successor as head of the Senate Foreign Relations Committee, Jesse Helms, of North Carolina, is so stridently partisan that he has deemed Mr. Clinton unworthy to be commander in chief.
Richard Lugar of Indiana, the committee's ranking majority member, is qualified by experience and temperament to be an effective reconciler of executive-legislative differences, but he holds no foreign policy leadership position in Congress.
That leaves Senate GOP leader Bob Dole of Kansas. Mr. Dole has the stature to fill a Vandenberg role, say analysts, but neither Vandenberg's gift for conciliation nor his love of foreign policy. ``I don't see him in the same kind of senior statesmen's role,'' says Robert Peabody, a political scientist at Johns Hopkins University. ``He has too much love for the jugular. An adversarial role is more appropriate for him.''
With an eye on the presidency, Dole has a major stake in avoiding the kind of criticism Vandenberg received from fellow Republicans for cooperating so closely with a Democratic president.
``To get the nomination he has to be the most Republican of Republicans,'' Dr. Peabody says.
THE advantage of having the support of a leading GOP lawmaker was demonstrated in the debate over the General Agreement on Tariffs and Trade this month. In a significant show of bipartisanship, Dole delivered crucial Republican votes.
The disadvantages have been illustrated by Dole's strident criticism of the Clinton administration's handling of the crisis in Bosnia. If approved, a Dole-backed, White House-opposed congressional resolution to unilaterally lift a UN arms embargo on Bosnia will leave the US with two foreign policies toward Bosnia and make it even harder for Clinton to manage relations with the Western allies and Russia.
Diplomatic analysts note that even in the heyday of bipartisanship, consensus went only so far. Even as Democrats and many Republicans closed ranks on policy toward Europe and the Soviet Union, they engaged in intense partisan debates over how to deal with China, Latin America, and the Palestinians.
The difficulty of finding foreign policy consensus today, they add, goes far beyond Senators Helms and Dole. Shifts and turns in Clinton's foreign policy have been an obstacle to consensus.
A more stubborn obstacle is the changed nature of the world. Where it once had a central organizing principle - the containment of communism - it has less coherence in a post-cold-war world where power is decentralized and strength no longer calculated in purely military terms. It has become more difficult to define threats to the national interest or even to define the national interest itself.
The decentralization of threats is mirrored in the decentralization of the foreign-policy process itself. Once the nearly exclusive domain of the president, Congress and interests groups now have larger roles to play, undermining a tradition of deference to the president in foreign affairs.
Bipartisanship has also been bedeviled by the attitudes of an ambivalent public that recoils at televised pictures of human rights abuses - as in Bosnia - but opposes sending US troops abroad.
In the absence of the kind of threat posed by the Soviet Union during the cold war, analysts conclude, fashioning a clear, coherent foreign policy and garnering the bipartisan consensus to go with it will be all but impossible.
``Even Vandenberg would have a hard time plowing his way through current circumstances,'' says Frederick Holborn, a professor of US foreign policy at the Johns Hopkins School of Advanced International Studies.