Challenging the White House, 59 former American diplomats are urging the Senate to reject John R. Bolton's (search) nomination to be U.S. ambassador to the United Nations.

"He is the wrong man for this position," they said in a letter to Sen. Richard Lugar (search), chairman of the Senate Foreign Relations Committee. The Indiana Republican has scheduled hearings on Bolton's nomination for April 7.

"We urge you to reject that nomination," the former diplomats said in a letter obtained by The Associated Press and dated Tuesday.

The ex-diplomats have served in both Democratic and Republican administrations, some for long terms and others briefly. They include Arthur A. Hartman (search), ambassador to France and the Soviet Union under Presidents Carter and Reagan and assistant secretary of state for European affairs under President Nixon (search).

Others who signed the letter include James F. Leonard, deputy ambassador to the U.N. in the Ford and Carter administrations; Princeton N. Lyman, ambassador to South Africa and Nigeria under Presidents Reagan, George H.W. Bush and Clinton; Monteagle Stearns, ambassador to Greece and Ivory Coast in the Ford, Carter and Reagan administrations; and Spurgeon M. Keeny Jr., deputy director of the Arms Control Agency in the Carter administration.

Their criticism dwelled primarily on Bolton's stand on issues as the State Department's senior arms control official. They said he had an "exceptional record" of opposing U.S. efforts to improve national security through arms control.

But the former diplomats also chided Bolton for his "insistence that the U.N. is valuable only when it directly serves the United States."

That view, they said, would not help him negotiate with other diplomats at the United Nations.

Adam Ereli, the State Department's deputy spokesman, responded: "He is a great nominee. We hope he will be confirmed. And we look forward to his getting to New York to do the nation's business."

Bolton, who rarely muffles his views in diplomatic nuance, was nominated March 7. Secretary of State Condoleezza Rice described him as "a tough-minded diplomat" with "a proven track record of effective multilateralism."

Bolton promised to work closely with members of Congress to advance President Bush's policies and said his record demonstrates "clear support for effective multilateral diplomacy."

Approval of the nomination requires a majority vote from the Senate committee, which has 10 Republicans and 8 Democrats.

In the letter, the former diplomats praised Bush's efforts at the start of his second term to improve relations with European allies and with the United Nations.

It is for that reason, they said, "we write you to express our concern" with Bolton's selection.

They ticked off a number of treaties they said Bolton had opposed and said he had made "unsubstantiated claims" that Cuba and Syria were working on biological weapons.

Also, they said Bolton had worked as a paid researcher for Taiwan and supported recognition of it as a sovereign state, and said he was skeptical of U.N. peacekeeping operations.

"Given these past actions and statements, John R. Bolton cannot be an effective promoter of the U.S. national interest at the U.N.," the former diplomats concluded. "We urge you to oppose his nomination."