Secretary-General Ban quite clearly is more willing to increase the United Nations’s involvement in Iraq — and to be more helpful to America there — than his predecessor, Kofi Annan. But what can the organization actually do there?

Iraq’s traditional rivalries are based on religion, ethnicity, and family ties. An organization such as the United Nations, in theory, has the tools to navigate such a political maze, including being able to quietly talk to characters Washington deems too unsavory for direct dialogue. According to another theory, however, Washington says the United Nations should play a role, but wants instead to pull the organization’s strings.

Some former Saddamites — Iraqi nationalists who oppose the Saudi-backed foreigners involved in the anti-American insurgency — could be coaxed by a good negotiator to help build a bulwark against Al Qaeda in Sunni-controlled areas. Similarly, Iran-weary nationalists among southern Iraq’s Shiites could be strengthened if such a negotiator could get to them. A seasoned, preferably Arab-speaking, U.N. diplomat may be best suited to become that negotiator. But even as the Security Council voted on Friday to expand the United Nations’s role in steering Iraq’s political future, it is doubtful that Mr. Ban currently has such a man at his disposal.

The leading candidate to become Mr. Ban’s personal representative in Baghdad, the Swedish U.N. diplomat Staffan De Mistura, is considered better at coordinating humanitarian assistance than at playing Middle East politics. In a previous appointment as the U.N. envoy in Beirut, Mr. De Mistura was seen more as a stopgap than a diplomatic wizard steering Lebanon’s national reconciliation.

Much attention was given to a public endorsement he received from America’s ambassador to the United Nations, Zalmay Khalilzad. But even as he backed Mr. De Mistura’s Iraq candidacy in a Friday interview with the Washington Post, Mr. Khalilzad added this largely overlooked line: “A more prominent international figure could be invited to lead the Iraq talks in the future.”

Prominent international figures, however, are not standing in line to go to Iraq. For one, serving the United Nations is not as desirable as it once was for ambitious diplomats. Bernard Kouchner was at one point mentioned as candidate for the U.N. Iraq post, but then he got a better offer and now serves as France’s foreign minister.

Despite its prominence, Iraq is also not an attractive diplomatic posting. “My children are older now, and they watch the news,” a U.N. diplomat told me recently. “If I am sent to Baghdad, they will object.”

Similar concerns may have warned off a French diplomat, Jean Arnault, who was reportedly on Mr. Ban’s short list of candidates. Raising a young family, Mr. Arnault prefers a relatively habitable capital, such as Khartoum, Sudan, to the dangers and oppression of the Green Zone, I am told. Nor does Turtle Bay provide much in the way of a supportive environment for a Baghdad diplomat. Objecting to a plan to increase the U.N. presence to 90 staffers, the organization’s Staff Union, citing security concerns, instead called for withdrawing its members from Iraq altogether. And even though Mr. Ban may want to help America and its allies in Iraq, many top officials of Mr. Annan’s era would rather rub the Bush administration’s nose in a humiliating defeat.

On the other hand, Mr. Khalilzad’s declared support for Mr. De Mistura may have another reason altogether. At least one theory making the Turtle Bay rounds is that Washington — or at least Mr. Khalilzad — prefers a U.N. representative in Iraq who is far less than a prominent international figure.

America’s success in Iraq is Mr. Khalilzad’s overriding U.N. interest, according to this theory, and publicly backing the U.N. Iraq representative allows the Bush administration to counter criticism from Democrats and Europeans about a lack of “international involvement” and “diplomacy.” Meanwhile, a weak U.N. representative in Baghdad can do America’s bidding.

According to one version of this theory, this thinking was quietly developed by Mr. Khalilzad along with an old ally, Lakhdar Brahimi, a former U.N. diplomat. In this version, two shrewd veterans of the Iraq game — Messrs. Khalilzad and Brahimi — would serve as the puppet masters pulling Mr. De Mistura’s strings.

Like Lebanon and the Palestinian Arab territories, to name two prominent examples, Iraq’s much-undermined pre-statehood state is one of the biggest challenges we all face in the Middle East. In Iraq, the United Nations has long been all but absent. It may yet have to wait a while before it truly becomes a player.