Updated

The Bush administration is sticking with its timetable to turn over power in Iraq, despite speculation that more time may be needed for the handover.

"The United States and our coalition partners are continuing to work closely with Iraqi leaders and the Iraqi people on our plan to meet the June 30th deadline," White House spokesman Brian Besanceney said Sunday.

On Sunday, the chairman of the Senate Foreign Relations Committee (search) raised the prospect of extending the June 30 deadline, questioning whether the country would be ready by then for self-rule.

Sen. Dick Lugar (search) said security is a shambles in some cities, and Iraqi police forces are not prepared to take over.

Eight U.S. soldiers were killed in fighting Sunday with Shiite militiamen in the Baghdad neighborhood of Sadr City (search).

The U.S. military also reported that two Marines were killed in a separate "enemy action" in Anbar province Saturday, raising the toll of American service members killed in Iraq to at least 610.

"The real issue is June 30, how we are going to make that transition," the Indiana Republican said on ABC's "This Week."

The key, he said, is that "even as we're trying to get security, which we must, and Iraqis take on more security, there will be enough going there that, in fact, the democratic forces can have the constitution building, they can have the elections, can have the transition."

Asked whether transferring power in less than three months would be too soon, Lugar said, "It may be, and I think it's probably time to have that debate."

Under current plans, Iraq would no longer be under U.S. political control on June 30, but more than 100,000 American troops would remain in the country. U.S. officials have said the Army is assuming it will have to keep roughly 100,000 troops in Iraq for at least another two years.

White House spokesman Besanceney said Sunday: "The United States will stay in Iraq until the job is done and there is a free, peaceful and democratic Iraq for the Iraqi people. A free and peaceful Iraq is critical to bringing about greater stability in a dangerous region of the world."

Lugar, who plans committee hearings on Iraq this month, said there remain far too many questions about what will happen after installation of an interim government, whose composition has yet to be decided.

He said the administration has not told his committee its plans for an ambassador, who the 3,000 embassy staff will be and how they and the embassy will be protected.

"This is a huge new exposure of Americans," Lugar said. "At this point, I would have thought there would have been a more comprehensive plan."

Delaware Sen. Joseph Biden, the committee's top Democrat, said training Iraqi forces cannot be done in months but will require a minimum of three years.

"We're going to end up with a civil war in Iraq if, in fact, we decide we can turn this over, including the bulk of the security, to the Iraqis between now and then," Biden told "Fox News Sunday."

Iraq has seen some of its worst violence in the past month.

Last Wednesday, jubilant crowds dragged the burned, mutilated bodies of four American civilian security guards through the streets of Fallujah. That same day, five U.S. troops were killed in a roadside bombing just northwest of the city.

Sunday saw the worst unrest in Iraq since the spasm of looting and arson immediately after the fall of Saddam Hussein, as supporters of an anti-American cleric rioted in four cities.

In a Washington Post op-ed piece published Sunday, Biden urged President Bush to sponsor a summit meeting on Iraq with European allies, including those who opposed the war. He also said the United States should push a plan for the United Nations to create a high commissioner, whose job would be to manage Iraq's political transition.

"We need to, in my view, take the total American face off of this," Biden said. The administration has been under pressure from its Iraqi partners and international allies to transfer power to the Iraqis and end the military occupation as soon as possible.

The administration also wants a functioning, sovereign Iraqi government in place to counter Democratic criticism of Bush's Iraq policy during the campaign for the Nov. 2 presidential election.