President Clinton said today that a global nuclear test ban treaty is more essential now than it was when it was first proposed at the height of the Cold War and that rejecting it would be a "dangerous U-turn" from the United States' role as the leader in halting the spread of nuclear weapons.

A day after bowing to Republican demands that he request a delay of next week's scheduled Senate vote on ratification of the test ban--which has been signed by 154 nations but ratified by only 48--Clinton said if the GOP-controlled Senate is not prepared to "seize the priceless chance . . . for a safer world," it should debate it thoroughly and work on a bipartisan basis to approve the pact.

"The stakes are high," Clinton said in his weekly radio address, delivered shortly before he spoke to a group of Hispanic leaders here and before he castigated Senate Republicans for blocking the confirmation of Hispanic judges he has nominated to the federal bench.

Clinton accused the GOP-led Senate of ignoring minority nominees to federal judgeships but assured the 8,000 delegates to the annual U.S. Hispanic Leadership Conference that, despite the confirmation delays, "more and more, America will look like you."

Declaring in his radio address that there is more urgency to ratify the Comprehensive Test Ban Treaty now than when President Dwight D. Eisenhower proposed it more than 40 years ago, Clinton said Republicans had "politicized" the issue, with many of them committing "to vote against it without even giving the issue serious consideration or hearing arguments."

If voted down, the pact would be the first treaty to be rejected by the Senate since the Treaty of Versailles, which established the League of Nations after World War I--a conflict that was followed by the Depression and World War II, Clinton noted.

Many Republicans have raised doubts about whether the United States could trust the other signatory nations to refrain from conducting tests. They have cited the concerns raised by intelligence agencies that the monitoring of tests is not foolproof. And they have pointed to testimony by nuclear weapons engineers that the reliability of U.S. nuclear weapons cannot be ensured without at least occasional test explosions. Were a vote held next week, the treaty--which Clinton signed in 1996 and submitted to the Senate in 1997--would not receive the 67 votes needed to ratify, both sides agree. That is why Clinton has requested a delay.

Arms Services Committee Chairman John W. Warner (R-Va.) is trying to get a majority of senators to support delaying the vote until after a new Congress is elected next November.

Warner said in an interview that he is gathering commitments for signatures on a letter to Senate leaders saying that, if an agreement is reached to put off the vote, the treaty should be returned to the Foreign Relations Committee and should stay there until the 107th Congress convenes in 2001. "It would be an expression of a majority of senators that, if the president and the leaders work out an agreement, we will exercise our right to assure this is not brought up again in this Congress," Warner said.

Many Republicans have demanded such an assurance from Clinton and the Democrats as one of the conditions for a delay in the vote.

Clinton, in his address, said that every year of delay in ratifying the treaty increases the threat that nuclear weapons will spread in the Middle East, the Persian Gulf, Asia and other regions with intense rivalries, as well as to "rogue leaders and perhaps even to terrorists."

Rejecting the treaty "would say to every country in the world, 'Well, the United States isn't going to test, but we're giving all of you a green light to test, develop and deploy nuclear weapons,' " Clinton said. Noting that both India and Pakistan exploded nuclear bombs last year but now have indicated a willingness to sign the treaty, Clinton said, "If the Senate defeats it, can we convince India and Pakistan to forgo more tests?"

The president added: "If our Senate defeats it, what will prevent China, Russia or others from testing and deploying new and ever more destructive weapons?"

He said 32 American Nobel laureates in science and other leading scientists had testified in the Senate that the United States does not need to test more bombs to ensure a "safe and reliable nuclear force." He noted their explanation that, since the United States stopped testing in 1992, it has developed "proven" programs costing $4.5 billion a year that use computer models and elaborate spot checks to ensure the reliability of aging weapons.

Clinton said that without a treaty, "other countries can test without cheating and without limit." With one, he said, "we could catch cheaters and mobilize the world against them. None of that will happen if we don't ratify the treaty."

But House GOP Conference Chairman J.C. Watts (R-Okla.) said the treaty is not only "unverifiable" but would increase U.S. vulnerability to nuclear attack because "rogue nations" such as China, Pakistan, North Korea, Iraq and Iran are unlikely to ratify it.

While Warner may be seeking to delay the vote in the Senate, Watts said: "Unfortunately . . . this dangerous treaty will not get better with age. The Senate should reject it in the best interests of U.S. national security."

The Hispanic leaders here greeted Clinton enthusiastically, waving red, white and blue kerchiefs and cheering him on the last stop of a three-day trip that included speeches to labor union members and gay groups in New York.

The U.S. Hispanic population is projected to become the nation's largest minority group by the end of 2004. Although 72 percent of the 18.5 million Hispanics who voted in the 1996 presidential election voted for Democrat Clinton, Texas Gov. George W. Bush--the front-runner for the GOP nomination next year--has made a strong bid for Hispanic support.

Clinton said that while Hispanics are moving quickly into "the mainstream of American life," the Senate has dragged its feet on confirming his Hispanic judicial nominees. He mentioned Richard Paez, the first Mexican American to serve as a federal judge in Los Angeles, whom Clinton nominated to the 9th U.S. Circuit Court of Appeals more than three years ago.

"They don't want to vote him down because they hope that you will vote with them in the next election, but they don't want to vote for him. So this man has been hanging there for 3 1/2 years," Clinton said.

He called a "disgrace" the Senate's party-line rejection of Missouri State Supreme Court Judge Ronnie White, who is black, for a federal judgeship. "It was wrong, and that's the kind of thing that should stop," Clinton declared.

"The Senate's treatment of Judge White and its failure to vote on the outstanding Hispanic nominees that are pending creates a real doubt about the Senate's ability to fairly perform its constitutional duties to advise and consent," Clinton said.

But Sen. John D. Ashcroft (R-Mo.) noted that the rejection of White had only to do with his "soft-on-crime, anti-death penalty record on the Missouri Supreme Court." He said, "Law enforcement groups strongly opposed the nomination. Few senators would even have been aware of the nominee's race."

Staff writer Helen Dewar in Washington contributed to this report.

CAPTION: President Clinton decries the delay in Hispanic nominees' confirmation.