Carlos Valenzuela is no stranger to organizing elections in troubled lands. The long-haired, jeans-clad United Nations official has worked in Cambodia, where voters were shelled at polling places in 1993, and East Timor, where attacks by armed gangs and Indonesian soldiers emptied entire villages ahead of a 1999 referendum. But as the head of the U.N. elections mission in Iraq, the 46-year-old Colombian may be on his ultimate Mission: Impossible. He's a virtual prisoner in his sparsely furnished U.N. office, unable to venture out of Baghdad's heavily fortified Green Zone. With elections for a national assembly scheduled for the end of January, Valenzuela disputes Iraqi Prime Minister Ayad Allawi's claim that voting could be held now in 15 of the country's 18 provinces. "I would be lying if I said even 15 are secure enough to be ready for elections," he says. "[But] the elections don't have to be perfect. What we're looking for is an election that is credible."

So is the Bush administration, and some of its senior officials have begun suggesting that not every town or city has to participate. "Let's say you tried to have an election," mused Defense Secretary Donald Rumsfeld, "and you could have it in three quarters or four fifths of the country, but some places you couldn't because the violence was too great. So be it. Is it better than not having an election? You bet."

The problem is this: under current rules, eligible voters will cast ballots as though Iraq is a single national constituency. The system is designed to encourage national parties and to reduce ethnic tensions. But if Sunni areas are excluded, the Sunnis will be disenfranchised, and they're already the most alienated group in the country.

Rumsfeld's blunt remarks drew quick retorts--from within the U.S. government. Deputy Secretary of State Richard Armitage publicly contradicted Rumsfeld by reaffirming the administration's policy of wanting to hold elections "in all parts of Iraq." State Department officials, who did not want to be named, were flabbergasted. They fear that elections that exclude the Sunni heartland are a formula for civil war. Iraq's most prominent (and moderate) Sunni, President Ghazi al-Yawar, lashed out at the proposal: "It is very appalling, and if somebody tries to shove it down our throats, we'll throw it out," he told CNN.

U.S. officials are determined to hold the vote by Jan. 31. The new parliament would then choose a prime minister from the party with the largest number of seats to replace Allawi's interim administration. And then the national assembly would begin drafting a constitution, laying the groundwork for a fresh round of national elections in 2006.

Americans now are scrambling to find a formula that would enable a vote without disenfranchising the Sunnis, who are 20 percent of the population. One proposal under review would divide Iraq into districts with a number of assembly seats assigned to each of them, similar to the system used to elect the U.S. House of Representatives. If voting could not take place on the designated date in one or more of these districts, the balloting there would be rescheduled for a later time. But in a country with no proper census, where districts have not been well defined, this is a recipe for conflict. (Think Florida with lots of armed gangs, terrorists, badly trained cops and a hated occupation army.)

An alternative scenario envisions a "hybrid" election in which Shiites and Kurds vote in the national-assembly election while a percentage of seats in the parliament is set aside for the Sunni minority. U.N. sources told NEWSWEEK this idea is a nonstarter, but some U.S. officials want to pursue it. "We don't want to delay elections, and Allawi doesn't want to, either," said one.

The registration process for 12 million voters is supposed to kick off at the start of November. But the U.N. elections team in Iraq has only eight international staffers, a fraction of the three dozen advisers who are supposed to be in place for the voting. Up to 120,000 election workers will be needed to man 30,000 polling places nationwide, and training programs under U.N. auspices got underway in Jordan only last month. Whatever is decided, it had better be soon.

WITH ROD NORDLAND IN BAGHDAD AND MARK HOSENBALL AND EVE CONANT IN WASHINGTON