Lost amid the news of all the bloodletting in Iraq is an important political development: The Kurds have switched sides. In the first parliament after the first set of elections, they allied themselves with the Shi'ite slate to produce the current Shi'ite-dominated government led by Ibrahim al-Jafari. Now the Kurds have joined with the opposition Sunni and secular parties to oppose the Shi'ite bloc. The result is two large competing coalitions: (a) the Kurd-Sunni-secular bloc, which controls about 140 seats in the 275-seat parliament and would constitute the barest majority, and (b) the Shi'ite bloc, which itself is a coalition of seven not-always-friendly parties, and which controls 130 seats, slightly less than a majority. If only it were that simple, Iraq would have a new secular-oriented government. But to protect minorities and force the creation of large governing coalitions, the Iraqi constitution essentially requires a two-thirds majority to form a government. If we had that requirement in the US, we might still be trying to settle the 2000 election. In Iraq, the result for now is stalemate, which could lead to disaster if the whole system disintegrates because of the impasse. Or it could lead to a more effective, less sectarian government than Jafari's. The key question is who is going to control the two critical ministries: interior and defense. In Iraq, as in much of the world, interior does not control the national parks. It controls the police. And under the current government it has been under Shi'ite control and infiltrated by extreme Shi'ite militias. Some of these militias launched vicious reprisal raids against Sunnis after the bombing of the Golden Mosque in Samarra, jeopardizing the entire project of a national police force exercising legitimate authority throughout the country. The main objective of US Ambassador Zalmay Khalilzad, who worked miracles in Afghanistan, is to make sure that the Interior Ministry is purged of sectarianism by giving it to some neutral figure, perhaps a secular Sunni with no ties to the Ba'ath Party. Similarly with the Defense Ministry, which controls the army. The army has, by most accounts, handled itself well following the mosque bombing and subsequent riots, and has acted as a reliably national institution. It is essential that it not get into sectarian hands. Political success in Iraq rests heavily on these two institutions. Which is why these negotiations, tiresome and endless as they seem, are so important. THE IMMEDIATE issue is the prime ministership. An internal ballot among the Shi'ite bloc chose, by a single vote, another term for Jafari. The critical vote putting him over the top was the faction controlled by Moqtada al-Sadr, the radically anti-American and pro-Teheran cleric whose home base is the Shi'ite slums of Baghdad. For Sadr, a weak and corruption-ridden government that allows conditions to deteriorate would be the perfect prelude to his gaining power. Not all parts of the Shi'ite coalition are happy either with Jafari's ineffectiveness or with his political dependence on Sadr. Splits are already appearing in that uneasy alliance. But the most important challenge to Jafari is the Kurds. They are wary of Sadr and unhappy with Jafari, under whom everything - services, security, trust - is deteriorating. Admittedly, part of their calculation is sectarian. This is, after all, Iraq. Jafari has impeded Kurdish claims on Kirkuk and infuriated the Kurds by traveling to Turkey (which opposes all Kurdish ambitions) without their approval and with a traveling party that did not include a single Kurd. The Kurd-Sunni-secular bloc wants a new prime minister who will establish a national unity government. Because the US wants precisely the same outcome, the Kurd defection is very good news in a landscape of almost unrelenting bad news. The other good news is a split in the Shi'ite bloc, with a near majority that favors a more technocratic prime minister and is chafing at Sadr's influence. Additionally, the Sunni insurgency is in the midst of its own internecine strife between the local ex-Ba'athists who are not particularly religious and want power, and Abu Musab al-Zarqawi's foreign jihadists, for whom killing Shi'ites combines sport and religion, and who care not a whit for the future of the country. There are numerous reports of Sunni tribes declaring war on these foreign jihadists and of firefights between them. The security situation is grim and the neighboring powers malign. The one hope for success in Iraq is political. The Kurdish defection has produced the current impasse. That impasse has contributed to the mood of despair here at home. But the defection holds open the best possibility for political success: an effective broad-based national unity government which, during its mandatory four-year term, presides over an American withdrawal. The writer is a Washington Post columnist.