Baghdad, Iraq ? The top U.S. administrator in Iraq insisted Thursday there were many ways to choose a new Iraqi government but a June 30 deadline for handing over power remains firm. Hours later, the United Nations backed Washington’s claims that a direct vote before then was impossible.

The U.N. judgment on elections throws open the debate over how to transfer sovereignty and end the U.S. occupation — though not the U.S. military presence — among Americans, Iraq’s Governing Council and powerful Shiite Muslim clerics, who derailed U.S. plans by demanding an early direct vote.

Iraqi leaders have largely turned against the original American plan to use regional caucuses as the basis for the new government. The Bush administration hopes that U.N. Secretary-General Kofi Annan will now endorse an alternative that would expand the Governing Council and hand it power to rule until elections, a U.S. official told The Associated Press.

Support is growing within the U.S.-appointed council for expanding the body, several members said Thursday.

The council is also due to finish drafting an interim constitution next week, resolving the key questions of federalism and the role of Islam in the government. While calling for any charter to acknowledge the Islamic nature of Iraq, U.S. administrator L. Paul Bremer said the law must be based on secular democratic principles.

In New York, Annan did not give any recommendations on how to pick a provisional government. He has reportedly said he wouldn’t weigh in on that issue before Wednesday.

But after his special envoy, Lakhdar Brahimi, briefed representatives of 45 nations and the European Union on his weeklong visit to Iraq, Annan told reporters an early vote was not feasible.

“We shared with them our sense — and the emerging consensus or understanding — that elections cannot be held before the end of June, that the June 30 date for the handover of sovereignty must be respected, and that we need to find a mechanism to create a caretaker government and then prepare the elections … sometime later,” Annan said.

Iraq’s top Shiite cleric, Grand Ayatollah Ali al-Husseini al-Sistani, disrupted the American plan for the handover by calling for an early election and opposing caucuses. Most of the Governing Council’s 25 members, who agreed to the caucuses in November, now say they want that formula dropped.

“Changes are possible but the date holds,” Bremer told reporters.

“There are literally dozens of ways in which to carry out this very complicated task,” he said, including variations on the caucuses or “varying other kinds of elections, partial elections.”

The Bush administration is under pressure from its Iraqi partners and international allies to yield power and end the military occupation as soon as possible. It is also eager to give Iraqi security forces a frontline role against guerrilla violence.

Iraqi clerics and tribal leaders gather at a Sunni Muslim mosque in Baghdad to call for unity among Sunni and Shiite Muslims and to discuss the future of Iraqi governance. U.N. Secretary-General Kofi Annan said Thursday he agreed with the American assessment that holding legislative elections in Iraq before June 30 would be impossible.