President Bush said Wednesday he is confident he can work out a new security pact with the Iraqis before year's end. But time is running out and the two sides may be forced to ask for an extension of the current U.N. agreement allowing the U.S. military to operate in Iraq.

Doing so would shift crucial decisions about U.S. military power in Iraq to the next U.S. president.

Political opposition to the proposed deal in Iraq has increased discussion in Washington and Baghdad about a U.N. extension. The Iraqi Cabinet this week authorized Iraqi Prime Minister Nouri al-Maliki to reopen talks on the Status of Forces Agreement, and he has sent proposed changes to Washington.

"We're analyzing those amendments," Bush told reporters in the Oval Office during a meeting with Massoud Barzani, the president of the semiautonomous Kurdish region in northern Iraq. "We obviously want to be helpful and constructive without undermining basic principles. And I remain very hopeful and confident that the SOFA will get passed."

The current U.N. mandate gives legal authority for U.S. forces to operate only through Dec. 31. Iraq considered the mandate an affront to its sovereignty and sought a replacement agreement with the U.S. that functions more like a treaty between equals. Negotiations began in May; the Bush administration had hoped to complete them by the end of July.

Some in the administration now worry it may be too late to get the Iraqi Parliament to approve the deal before the mandate expires. If a deal is not reached and the mandate not extended, American troops would be confined to their barracks and all operations would have to be suspended.

Security "gains that have been made will start to unravel potentially because we don't have a legal mandate to operate," Pentagon spokesman Geoff Morrell said Wednesday.

U.S. officials say they are working for a comprehensive deal and that there is no active effort to draft a temporary extension to the U.N. mandates. "I don't think anyone has put pen to paper on anything," State Department spokesman Sean McCormack.

Some administration officials, though, argue it is time to begin laying the groundwork to go back to the U.N. Security Council. Getting an extension to the mandate would require the approval of Russia and China, which hold veto power on the council.

Russia has signaled it could support an extension. China is expected to go along with Russia's vote. Although potentially welcome, that assent would come at the potential price of leverage, real or perceived, over the next U.S. administration. Some U.S. officials are reluctant to give either country that bargaining chip, especially after the Russian war with Georgia in August.

U.S. and Iraqi negotiators completed a draft text this month that would keep U.S. troops in Iraq through 2011 unless both sides agree they could stay longer. It would give the Iraqis a greater role in U.S. military operations and allow Iraqi courts to try U.S. soldiers and contractors accused of major crimes off duty and off base.

There is significant Iraqi opposition to the draft and the move to reopen the talks took on heightened significance after a dramatic weekend U.S. raid on Syria staged from inside Iraq.

Iraq now wants the agreement to include a clear ban on U.S. troops using Iraqi territory to attack its neighbors, government spokesman Ali al-Dabbagh said Wednesday. He said Iraq wants the right to declare the agreement invalid should that happen.

That ban is among four proposed amendments the Iraqis have submitted. The others include a clear definition of "duty" when cases arise involving crimes committed off base by U.S. troops and the right to inspect all U.S. military shipments entering or leaving Iraq.

"The Americans must realize that these changes are necessary to enable the government to persuade the people to accept the agreement," al-Dabbagh said.

U.S. officials have said the existing draft text is its final offer. But with time running out on both the mandate and Bush's term, they have agreed to at least consider the Iraqi proposals. At the same time, they insist changes will not be taken lightly.

"The bar to any revisions is very high," McCormack said.

But he insisted that no one in the administration was yet working on the alternative: extending the U.N. mandate. "There is a still a lot of life left in the process and it's really the focus of our efforts," he said.