Secretary of State Condoleezza Rice now faces the biggest crisis of her career. America's role in the Middle East is in danger of falling apart — and it is her job to put it back together. As she sifts through the damage wrought by the monthlong conflict in Lebanon and witnesses the intensifying violence in Iraq, her political future and vision of U.S. foreign policy as a transforming force in the Middle East hang in the balance.

This, like none other, is Rice's moment.

Nothing she has done quite prepares her for this role. Throughout nearly a decade in government, Rice has combined many talents — a striking public persona, political savvy, a knack for the bureaucratic infighting inherent in U.S. foreign policy, and the ability to avoid blame when things go awry. (Americans unhappy with the war in Iraq have largely given her a free pass, focusing their anger on President Bush, Vice President Dick Cheney and Defense Secretary Donald Rumsfeld, even though Rice has been involved in many key decisions.) Today, those talents will not suffice. Rice's chances of lasting success in the Middle East rest upon different skills: hard diplomacy, the shrewdness to craft a long-term strategy and the flexibility to make compromises that square with her proclaimed ideals. Rice has adapted before, from young pianist to academic Sovietologist, from Condi the bureaucratic straddler to Condi the Bush foreign-policy apostle. But this challenge is tougher than the others she has faced. Right now, the Middle East is Condi's war — and so far, she isn't winning.

Aug. 11's U.N. resolution ending hostilities between Israel and Lebanon — which Rice hammered out together with U.S. allies — is a critical breakthrough, but only the first step in an arduous effort to stabilize the region. After the war broke out, Rice traveled to the region and met repeatedly with some of its leaders, though not those in Iran or Syria.

At the outset, she stumbled badly in her rhetoric: When she argued that the war represented the "birth pangs of a new Middle East," she provided ready fodder for ridicule and anti-American diatribes throughout the region. It was not the time or place to take on the mantle of the apostle.

If Rice fails and the turmoil in the Middle East worsens, the adulatory coverage of her tenure at the State Department will dry up. For the first two years, the public perceptions of Rice — the boots! the dresses! the snooze on the floor of the plane! — concentrated more on her personality than on her modest diplomatic record.

So far, as secretary, Rice has worked hard, with some success, to improve relations with European governments and to ease the hard-edged unilateralism that typified Bush's first term. But she has failed to produce far-reaching diplomatic breakthroughs on more urgent problems, such as North Korea's nuclear program.

Her two immediate predecessors should provide cautionary tales: Both Madeleine Albright and Colin Powell received similar celebrity treatment in their early days at State, yet both ended their tenures there amid considerably less excitement than when they started.

Of course, Rice enjoys the one asset that these two predecessors lacked: a close working relationship with the president. Indeed, her ascent to the top of the Bush foreign-policy team was underscored less than three months ago when Bush agreed, at Rice's urging, to offer Iran direct talks over its nuclear program.

That action reversed more than two decades of U.S. policy; it also aroused outraged protests from neoconservatives such as Richard Perle, who accused the administration of "an ignominious retreat."

Rice's talent for bridging differences within the Republican camp was part of her appeal to George W. Bush when he first ran for president. Since the 1970s, the Republicans have been beset by divisions over foreign policy.

On one side are the realists, the wing of the party symbolized by former Secretary of State Henry Kissinger and former National Security Adviser (and Rice mentor) Brent Scowcroft; they emphasize balance-of-power diplomacy. On the other are the conservatives and neoconservatives, the wing symbolized by President Ronald Reagan; they put a premium on values, such as political freedom, in foreign policy.

These disputes had weakened the party and helped contribute to the defeat of two Republican presidents: Gerald Ford and, more important, George H.W. Bush, who was never able to win the support and enthusiasm of Reagan Republicans.

Rice's mission for the current president was to make sure it didn't happen again. She courted neoconservatives, suggesting that the differences within the party were more imagined than genuine.

During the 2000 campaign, in which Rice served as Bush's principal foreign-policy adviser, he gave speeches calling for "realism in the service of ideals."

Later, when the Bush administration drafted its first National Security Strategy in 2002, under Rice's direction, the document called for "a balance of power that favors human freedom." In each case, these careful formulations combine one nod to the Kissinger wing of the party (realism, balance of power) and one to the Reagan wing (ideals, human freedom).

As Bush's first-term national security adviser, Rice kept her distance from the bureaucratic combatants in this battle: the State Department vs. the Pentagon, Cheney and Rumsfeld vs. Powell. Younger and less-experienced than these top-level players, she failed to bring the internal discipline to the foreign-policy apparatus of the Bush administration that Scowcroft, her old boss, had brought to the administration of the president's father.

But in Bush's second term, Early Condi the straddler has given way to New Condi the apostle. She has emerged as the public spokeswoman for an interconnected set of ideas that make up the underlying justification for Bush's foreign policy: first, that the 9/11 attacks transformed international relations; second, that, as a result, many of the old assumptions about U.S. foreign policy should be thrown out; third, that the Bush foreign-policy team faces a task comparable to that of the Truman administration at the start of the Cold War, to develop an entirely new doctrine for this new era; and finally, that U.S. policy should be devoted to transforming the Middle East and bringing democracy to the region, a job that will take a generation.

Rice's new views, no doubt sincere, have again served Bush's political interests. Bush has now staked his presidency on the notion of an unending battle against terrorism. The speeches and news conferences of the New Condi provide the justifications and the historical analogies he needs to make his case.

The problem is that the notions of epochal change that Rice has put forward are exceedingly difficult to apply in the current chaos in the Middle East.

Take a typical news conference in Britain last spring. Asked about U.S. policy in the region, Rice replied: "I would say probably the most important thing that we've done is to declare ... that the 60 years of trying to buy stability at the expense of democracy in the region is now gone."

That was certainly forthright and cogent. But at the moment, Rice and the Bush administration would be thrilled to restore mere stability to the region. To do so, they probably will need the help of undemocratic governments such as those of Egypt and Saudi Arabia, the regimes to which Rice's gibe about "stability at the expense of democracy" was directed. They may even require the assent, at least tacit, of Iran and Syria. One way or another, once the Middle East goes up in flames, as parts of it have now, diplomacy there usually involves doing some business with nasty people. Unfortunately, the past 60 years of history can't be discarded; they are all too relevant.

Rice is no longer merely the conciliator of Republican disputes, or the national security adviser who reconciles differences within the bureaucracy, or the charismatic new face at the State Department.

Now, she is in charge of U.S. diplomacy at a time of great upheaval — and she will be held responsible for its failures.

The latest violence in the Middle East is a reminder that if things really fall apart, so will her own political prospects and the ambitious ideas she has worked so hard to advance.

James Mann is author in residence at Johns Hopkins University's School of Advanced International Studies and author of "Rise of the Vulcans: The History of Bush’s War Cabinet." He wrote this commentary for The Washington Post.