After a year-long vacancy in the post of U.S. ambassador to the United Nations, Richard Holbrooke will step into the job this week and begin the difficult task of restoring America's influence at the U.N., which has been chipped away committee by committee since U.S. arrears began climbing past the $1 billion mark in the mid-1990s.

While U.S. influence in the world may never have been greater, its standing in the United Nations has never been lower.

Because of its deadbeat status, the United States has been voted out of a seat on the key financial committee that vets the secretary general's biennial budget. Many of the U.N. reforms favored by Washington, such as a "sunset clause" to abolish committees that have outlived their usefulness, have faltered. And the United States is facing an enormous humiliation--the loss of its vote in the General Assembly--if it fails to pay at least $350 million of its arrears to the U.N. by Dec. 31.

In a display of rising contempt for Washington, the General Assembly has ignored American appeals to change the opening date of its next session, which this year falls on the Jewish holy day of Yom Kippur, forcing President Clinton to postpone his planned address.

And yet, while resentment toward the lone superpower is palpable at the United Nations, many here are as hungry as ever for American leadership and financial support. They are counting on America's most celebrated contemporary diplomat to restore the U.N.'s luster in the nation's capital.

"He's a perfect transmission belt between Washington and New York," said Mark Malloch Brown, the British-born director of the United Nations Development Program and a longtime friend of Holbrooke. "He wants to not just be Washington's ambassador to the United Nations, but the United Nations' ambassador to Washington."

The Senate confirmed Holbrooke three weeks ago after more than a year's delay caused first by an investigation of possible conflicts of interest in his work as an investment banker between diplomatic posts and, later, by "holds" placed on his nomination by a few Republican senators who wanted bargaining chips in unrelated disputes with the Clinton administration.

With only a year and a half remaining until the end of President Clinton's term, Holbrooke will need to move quickly if he is to resolve festering issues that have bedeviled his predecessors: breaking a deadlock in the Security Council over U.N. policy in Iraq and getting U.N. disarmament experts back into the country, persuading Congress to pay $1 billion (or $1.6 billion by the U.N.'s count) in U.S. arrears and convincing other countries that they should accede to congressional demands to reduce the U.S. share of the cost of the United Nations and its peacekeeping missions.

"Holbrooke is playing with a weak hand because the United States doesn't pay its dues, but that doesn't take away from the fact that the United States is the essential country," said a European diplomat. "Without the United States, the United Nations is not credible."

Over the coming months, the General Assembly will be asked to approve from $500 million to $600 million to fund the U.N. mission in Kosovo. One of Holbrooke's duties will be to deflect attempts by other countries to hamstring the mission. In recent weeks China, Cuba and Uganda have blocked $70 million for Kosovo, arguing that there were other, equally needy missions in Africa.

"I have written every [U.N. delegate] telling them, 'Send cash, we can't operate without it, we have no resources,' " said Joseph Connor, the U.N.'s undersecretary general for management. "This is not a situation where we can delay payments. In Kosovo, we're paying for policemen. If we don't pay them, they go home."

Holbrooke, who will be sworn in as ambassador in a low-key ceremony at the U.N. tomorrow, told Congress during his confirmation hearings that his top priorities will be managing emergencies such as Kosovo, fighting to get the U.S. back on the budget advisory panel and, above all, getting the U.N.'s financial house in order. "Budgetary discipline will be my watchword," Holbrooke told the Senate Foreign Relations Committee. "U.N. reform will be my highest sustained priority."

Some U.N. delegates openly question whether Holbrooke's reputation for knuckle-busting diplomacy--earned while negotiating an end to the Bosnian war in 1995 with Serbian leader Slobodan Milosevic--will serve him well in the chummy atmosphere of the United Nations.

"Today's adversary is tomorrow's friend. If you wish to maintain and enhance your influence you have to find a way to do it without rubbing people the wrong way," said Muhamed Sacirbey, Bosnia's former foreign minister and now its ambassador to the U.N. "You need to project power without letting anyone know you're doing it."

Other observers say that given the simmering hostility at the U.N. toward the United States, Holbrooke will have to resist the temptation to take center stage, relying at times on friendly nations to press the American agenda.

"The United States has no credibility in pushing any kind of measures; it can't be the prime mover," said Jeffrey Laurenti, an analyst at the United Nations Association. "If they have something they want done, they have to find someone else to take the initiative."

Connor, the U.N.'s top financial officer, predicts that Holbrooke will face two immediate tests.

In the fall, Secretary General Kofi Annan will submit the U.N.'s 2000-2001 budget, which contains an increase of about $100 million, to $2.6 billion, to keep pace with inflation. The budget, already endorsed by the General Assembly's budget committee, flies in the face of U.S. legislation that blocks the Clinton administration from approving any increase in U.N. spending. American efforts to trim the new budget have so far failed.

"If the United States believes zero nominal growth must be achieved, then they have to have someone here who can negotiate that," Connor said.

He added that Holbrooke will have an equally difficult time persuading his counterparts to accept a laundry list of American conditions--which include shrinking the U.S. share of the U.N. budget to 20 percent from the current 25 percent and forgiving nearly half a billion dollars in disputed dues--in exchange for U.S. payment of its arrears.

According to Connor, the United Nations already has undertaken difficult reforms, such as cutting 1,000 jobs by attrition, in return for which the United States was expected to pay its dues. "There is resentment that the quid pro quo hasn't happened," he said.

Both of Holbrooke's predecessors, Bill Richardson and Madeleine K. Albright, tried and failed to win payment of American arrears, which Congress last year tied to restrictions on U.S. funding for family planning organizations overseas, prompting a presidential veto.

Diplomats here are also mindful of what they perceive as Washington's disdain for the United Nations. They frequently note that the Security Council was not consulted before NATO's air war against Yugoslavia. They also say the U.N. was treated like an unwanted child by Holbrooke's negotiating team during the Dayton peace talks.

"I remember during the days of Dayton, the U.N. was a word that could not be uttered," recalled Carl Bildt, senior U.N. envoy to the Balkans. "The things that we were forced to do in terms of avoiding any association with the United Nations were really quite extraordinary."

In his testimony before Congress, however, Holbrooke sought to allay some of those concerns. He said he firmly believes that the United Nations is central to American national security interests. And when Sen. Joseph R. Biden Jr. (D-Del.) knocked the United Nations as a "well-intended, ofttimes slow and sometimes incompetent" organization, Holbrooke gently scolded him and his colleagues.

"In Bosnia, we weakened the [U.N.] High Representative's authority, and that was another one of our mistakes," said Holbrooke. "The goal here isn't to destroy the U.N. It's to reform it."

CAPTION: Ambassador Richard Holbrooke has said U.N. budget reform will be a top priority, but analysts say U.S. failure to pay dues has weakened his hand.