Washington ? Condoleezza Rice, the Russian-speaking scholar and polished personality whom President Bush tapped Tuesday to be secretary of state, is known for her expertise and poise.

But in her new role as chief ambassador for the United States, Rice will face conflicts that test her skills as a negotiator overseas while assuaging the skepticism of a State Department bureaucracy at home.

As a staunch supporter of the war in Iraq and a confidante of Bush, the world and Washington may well view Rice’s words as Bush’s own.

“The secretary of state is America’s face to the world,” Bush said Tuesday in nominating his national security adviser to lead the State Department. “And in Dr. Rice, the world will see the strength, the grace and the decency of our country.”

With remarks befitting a new secretary of defense as much as a chief diplomat, the president outlined the world role he envisioned for Rice: “We’re a nation at war. We’re leading a large coalition against a determined enemy. We’re putting in place new structures and institutions to confront outlaw regimes, to oppose proliferation of dangerous weapons and materials, and to break up terror networks.”

At the same time, Bush added, the United States will seek to achieve peace in the Middle East: “Meeting all of these objectives will require wise and skillful leadership at the Department of State.”

Bush is replacing Rice with her deputy at the National Security Council, Stephen Hadley. Rice’s nomination requires Senate confirmation, but Hadley’s appointment does not. Rice will seek her own replacement for Deputy Secretary of State Richard Armitage, a close friend of departing Secretary of State Colin Powell.

As Bush enters his second term, he will count on Rice to lead the United States through a period of intensely difficult negotiations on topics including avoidance of nuclear arms in Iran, conflict with North Korea and pursuit of peace between Palestinians and Israelis.

President Bush, left, and National Security Advisor Condoleezza Rice arrive together in the Roosevelt Room of the White House as Bush prepares to announce that she is his choice as secretary of state. Bush turned to his most trusted foreign policy adviser, Rice, to lead U.S. diplomacy during his second term, replacing Secretary of State Colin Powell on Tuesday.

Predictions that Rice will turn U.S. foreign policy to the right are overblown, according to some State Department officials who have worked with her and a senior administration official close to Rice.

“She is her own person,” the official said. “As secretary of state, she would have a very different role heading a Cabinet agency, and the president would certainly expect her to play that different role.”

In contrast to Powell’s tendency to negotiate with and resist harder-line leaders within the White House and Defense Department, Rice is considered more likely to toe the administration’s line on the war on terrorism. But administration officials say Rice has sided with Powell and the State Department more often than some in Washington believe, including on issues related to the Middle East.