WASHINGTON (Reuters) - The White House and the Republican-controlled Congress, engaged in a high-stakes struggle over endorsing a global nuclear test ban treaty, sought Wednesday to postpone a Senate vote on ratification.

President Clinton, who has set nuclear non-proliferation as a top foreign policy priority, warned a defeat of the treaty in the Senate would make the spread of nuclear weapons more likely, encourage testing and set a poor example for nations looking to the United States for leadership.

``The message of not ratifying this treaty is: OK, we're not going to test but you guys have a green light,'' Clinton said at the White House. ``I don't think we ought to give a green light to our friends in India and Pakistan, to the Chinese or the Russians, or to people who would be nuclear powers. I think that would be a mistake.''

However, the White House indicated that Clinton might accept a delay in the Senate vote scheduled for next Tuesday.

``If senators in their wisdom believe that they need more time, they need more months to look at this, then we will certainly be open to looking at their concerns and looking at what the schedule is,'' said White House spokesman Joe Lockhart. He said Clinton would consider a delay of months, but opposed putting off the ratification vote until a new president takes office in January 2001.

Senior administration officials and senators said they feared next week's vote would fall short of the two-thirds majority needed to ratify the treaty and that rejection would draw condemnation of the United States by its allies.

``If the Senate rejects the treaty, the proliferation of nuclear weapons is more likely, posing serious challenges to our nonproliferation goals,'' Defense Secretary William Cohen told a Senate Foreign Relations Committee hearing.

``There should never be a rush to ratify something as complicated and comprehensive as this,'' said Cohen, a former senator from Maine and the only Republican in Clinton's Cabinet. ``This is the first hearing that has been held. There should not be...a quick vote, but rather a very thoughtful examination.''

Clinton told reporters: ``After two long years of inaction, one week is very little time for considered action.'' But he said, ``For now the vote is scheduled for Tuesday, and I will continue to aggressively argue to the Senate and to the American people that this is in our national interest.''

Germany and Japan, opening a U.N. review conference on the nuclear test ban treaty in Vienna, urged the United States to ratify it and set an example to the world.

``Ratification in Washington would send a strong signal in favor of the treaty, which is just what we are trying to do in Vienna,'' said German Foreign Minister Joschka Fischer.

More than 150 countries have already signed the treaty, but to take force it must be ratified by all 44 countries in the Geneva-based Conference on Disarmament that have nuclear reactors or research programs, including the United States.

Clinton signed the treaty in 1996 and sent it to the Senate for ratification early in 1997. After blocking attempts by Democrats to hold hearings and vote on the issue for more than two years, Senate Republican leader Trent Lott surprised everyone last week by suddenly announcing it would be rushed to the Senate floor for a vote.

Senators from both parties, caught in the political wrangle between Congress and the White House but impressed with the seriousness of the ratification decision, seemed to conclude that the vote should be delayed.

``We should not hold a vote on the CTBT this year,'' said Republican Sen. Chuck Hagel of Nebraska. ``This is far too important of an issue to rush into what will surely be a political vote. We are talking about the future of the United States. This is not a discussion that should be hurried for political or partisan gain.''

Secretary of State Madeleine Albright underlined the gravity of the vote in a letter to each Senate member.

``You and your Senate colleagues face a critical vote and carry the responsibility of deciding how best to build a safer future for America in a world where dangers abound. I ask you to look at this question, not in the context of the Cold War, but rather with respect to the range of emerging threats we face -- in South Asia, North Korea, the Middle East and elsewhere -- from the proliferation of nuclear weapons and ballistic missiles. The CTBT is a fundamental roadblock in the path of this trend toward proliferation,'' the letter said.

As the day wore on, Senate Republicans and Democrats appeared to lose their appetite for a prolonged confrontation. Aides said both Lott and Senate Democratic leader Tom Daschle are seeking a dignified way to resolve the issue and satisfy their parties.

``The current status is that we're still hopeful that we can reach some agreement that would preclude the need for a vote Tuesday,'' Daschle told reporters.