President Barack Obama's choice of Hillary Rodham Clinton as his secretary of state was considered at the time by some as a stroke of genius; by others, a cardinal error.

Then-Sen. Clinton had been his main primary opponent for the Democratic nomination. She had also taken what some considered to be a damaging-to-the party, indecently long time to drop out of the race when it was clear she would not win.

Some worried that as secretary of state she would not be able to carry out an "Obama foreign policy" and would instead seek to set out a track record that would serve as the basis for her to mount a 2012 or 2016 repeat run for the presidency.

Lying in the background to this day is the still-simmering Clinton urge to get back into the White House. It most recently manifested itself in former President Bill Clinton's support of one candidate for the Colorado Democratic senatorial nomination while Mr. Obama supported another. (Mr. Obama's man won.) Such support is normally provided to build up credit for future electoral campaigns.

The other, almost entirely inside-the-Beltway hypothetical plot line now in play is the idea that somehow Vice President Joe Biden and Mrs. Clinton will switch places, she becoming vice president and he becoming secretary of state, soon or in 2012. This would be possible, although only through constitutional gymnastics that would shake the republic and probably annoy most Americans to the point of distraction.

It's easy to see why the Clintons might like the idea. It is hard to ascertain what would be in such a switch for Mr. Biden, though he does have a deep interest in foreign affairs.

It is a terrible idea. Mr. Biden has sometimes made ill-advised comments and on occasion seems unnecessarily glued to Mr. Obama's side, but in general he has done a good job as vice president.

It should never be forgotten that one task of a vice president is to make the president look good by comparison. Neither back in 2008 when Mr. Obama was choosing his vice president nor now do I think Mrs. Clinton is well-suited for the job. Her husband's and her ambition for her to be president is understandable. At the same time, it is not exactly comforting for a chief executive to know that his principal deputy lusts for his job. Ottoman emperors frequently had their brothers strangled to avoid a comparable predicament.

In any case, with the imminent commencement of Middle East peace talks, Mrs. Clinton is about to have the opportunity to construct an historic agreement, completing or at least moving forward toward an accord between the Israelis and Palestinians and the resolution of a dangerous problem that has tormented the world for more than six decades.

A cold assessment of what Mrs. Clinton has achieved so far as leader of American diplomacy takes us strongly to a "is the glass half full or half empty?" conclusion.

So far she can show no points on the board, no agreements reached nor wars ended. It cannot be said that she has made an ascertainable dent in any of America's major foreign policy problems. These include the Middle East, the Afghanistan-Pakistan war, the India-Pakistan Kashmir dispute, Russia vs. Georgia, America's longstanding quarrel with Cuba or any of Africa's numerous conflicts -- such as those in Sudan, Somalia and the Democratic Republic of the Congo.

On the other hand, she has been most effective in getting around the world and establishing relationships with the main players in world politics, where she has been helped by her previous experiences as a senator and first lady. It was very important for her to do so.

Americans among themselves can usually get down to business quickly after meeting, even for the first time. People from other cultures, particularly in the Middle East, Africa, South Asia and East Asia, sometimes take quite a while before feeling that they have a good enough understanding of someone to talk business seriously. Mrs. Clinton was wise to take some time and travel a lot during her first 20 months on the job before undertaking anything major.

Now, even if she would have preferred not to take on the difficult task of trying to bring peace to the Middle East as her first major foreign affairs undertaking, the talks between Israeli Prime Minister Benjamin Netanyahu and Palestinian Authority President Mahmoud Abbas will start tomorrow, preceded by a dinner tonight, and Mrs. Clinton will be ringmaster.

There is every reason to believe that, given the stakes, Mr. Obama will play an important role in the process, as needed. That will probably be necessary, considering the nature of the beast.

But Mrs. Clinton will be the one front-and-center, cajoling and twisting the arms of Mr. Abbas and Mr. Netanyahu. There will also be present at the beginning President Hosni Mubarak of Egypt and King Abdullah II of Jordan, key neighbors of the Israelis and Palestinians, both of whose countries have a dog in the fight.

During these talks Mrs. Clinton will be able to draw on all of the experience she has gained in her first 20 months as secretary of state and in her previous career as Mr. Clinton's campaign organizer in Arkansas, as a lawyer, as first lady and as senator from New York.

This can be her finest hour to date. It is also hazardous work, a chance for her -- if things were to go wrong -- to suffer the diplomatic equivalent of her disastrous 1990s venture into health care reform.

Everyone -- we hope -- wishes her well: the people of Israel and Palestine; their neighbors in the Middle East who don't want more wars in the region; and, most of all, Americans, who would love to step back from two countries, Israel and Palestine, that are living in security and peace with each other and not constantly importuning the United States to meet their military, political and economic needs instead of our own.

It won't be easy, but she can do it.

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