The face of American power here is a 5-foot-1 woman who can charm foreign envoys even when she is enforcing policies that infuriate them. Anne W. Patterson, the acting U.S. ambassador to the United Nations, represents a stark contrast to the confrontational John R. Bolton, whom President Bush has nominated to represent the United States at the world body.

With Bolton's confirmation at risk, Patterson is leading U.S. efforts to grapple with a series of U.N. scandals, monitor the 191-member institution's multibillion-dollar peacekeeping enterprise, and reorient it to halt terrorism and the spread of the world's deadliest weapons.

Senior U.N. delegates say they value her pragmatism and they are in no hurry to see her replaced by Bolton.

"There are plenty of people who would like to see Bolton delayed indefinitely," one senior U.N. official said. "I haven't heard anyone saying we'd rather work with her than him, but obviously that's implicit."

John C. Danforth, the former U.S. ambassador to the United Nations, said the U.S. mission "clearly suffers" from not having an ambassador in place. But he noted that Patterson had exhibited the skills to run the large mission when she served as his deputy.

"I don't know how the Bolton nomination stands," said Danforth, who resigned in January. "But she could certainly do that job and anything else."

Patterson, 55, is a career Foreign Service officer and has headed U.S. embassies in El Salvador and Colombia. She is the first woman to serve as U.S. deputy permanent representative to the United Nations, the second-highest-ranking U.S. official here. Since Danforth's departure, she has been coping with a broad range of crises -- including a recent upsurge of violence in Haiti that may require the deployment of U.S. troops -- with a thinly staffed and undersupported mission.

Three of the mission's five ambassadorial posts, including Bolton's, remain unfilled (although the United States has temporarily assigned a retired senior diplomat to oversee U.N. peacekeeping). The Bush administration has yet to appoint an assistant secretary of state for the Bureau of International Organization Affairs, which oversees U.N. policy.

"The women is doing four jobs," said Catherine Bertini, a former senior adviser to Secretary General Kofi Annan and the top U.S. citizen at the U.N. Secretariat before leaving the organization this spring.

Patterson has won high marks from her colleagues and staff members, who describe her as a smart manager who listens to advice from her specialists. She has won praise from human rights advocates for her role in implementing one of the largest U.S. foreign assistance programs, Plan Colombia, while serving as ambassador to Colombia.

"Anne Patterson was an outstanding ambassador," said Jose Miguel Vivanco, Americas director of Human Rights Watch. Vivanco said that an unprecedented number of senior Colombian officers with alleged links to the country's paramilitary death squads were denied visas under her watch to travel to the United States. "She was never shy about raising human rights concerns or even criticizing publicly the poor record of the Colombian armed forces," he said.

But Patterson has also been targeted by congressional critics, who have faulted her role in scaling back a U.S.-backed opium-eradication program in Colombia in 2001 in order to step up spraying of Colombian coca. The decision coincided with an increase in heroin use in U.S. cities.

Patterson follows a succession of career diplomats who have served extended stints in the country's most visible diplomatic job outside Washington. A. Peter Burleigh served from September 1998 to August 1999 as the Clinton administration's top representative to the United Nations, filling in for Richard C. Holbrooke as he struggled through a protracted confirmation battle. James B. Cunningham ran the mission for about nine months in 2001 as congressional Democrats probed Bush's first U.N. ambassador, John D. Negroponte, about U.S. human rights policy in Honduras in the 1980s.

Like her predecessors, Patterson generally prefers operating below the radar screen, and she declined to be interviewed for this article. An aide said she did not want to be seen trying to grab the spotlight while her future boss is struggling through a bruising confirmation hearing.

Burleigh and other U.S. officials said the mission's deputy chief traditionally avoids the limelight, noting that any attempts to compete for attention with senior political appointees can damage a career. After serving at the United Nations, both Burleigh and Cunningham were blocked in Congress, for assignments in the Philippines and Vienna. Their troubles have given way to concern that the job may be cursed.

"There is a constant worry about a misstep," Burleigh said. "It would make a good story to say there was a curse, but I don't think so. But I suppose maybe we'll find out if Anne Patterson has problems in the future."

At the United Nations, Patterson has wielded America's diplomatic club with finesse. Syrian U.N. Ambassador Fayssal Mekdad, for instance, said he did not take it personally when she lectured his country for meddling in Lebanon's internal affairs.

"I know Anne Patterson very well; she's a nice person," Mekdad said. "Whenever we meet, we know that there are differences and we agreed that these differences should not interfere with our personal relations."

Patterson has also demonstrated a willingness to compromise, supporting a politically controversial decision to allow the Security Council to grant the International Criminal Court, which the United States opposes, a mandate to investigate war crimes by Sudanese officials in Darfur.

U.N. officials say they question whether a bargain could have been struck with Bolton, the Bush administration's most vocal critic of the international court. They also wonder whether her role in the deal would make it difficult for her to work with Bolton.

A U.S. spokesman at the United Nations said Patterson has no intention of leaving if Bolton is confirmed, but other officials say that she has shown interest in moving on. Mel Levitsky, a former U.S. ambassador who has known Patterson for years, said she has an interest in becoming the assistant secretary of state for the Bureau for International Narcotics and Law Enforcement Affairs, a post that frequently goes to political appointees.

"There is a natural tension between political appointees and career appointees and she absolutely bridged that," said Christopher Burnham, a former senior State Department official who oversees the U.N. department of administration. "I believe so strongly in Anne's talents that I hope that she will either stay on, or that the president will ask her to take on new and important responsibilities in Washington. I think it's important that this administration not lose a woman of such capability."

Anne W. Patterson has drawn praise as acting U.S. ambassador to the U.N. while John R. Bolton awaits confirmation.