WASHINGTON (AP) -- The Bush administration is set to miss another goal in Iraq today.

Today was the deadline the administration and Iraqi leaders had set themselves for agreement on what happens when the U.N. mandate runs out in December. But nothing is imminent, and White House Press Secretary Dana Perino says negotiating a deal on relations with Iraq has been a tricky business.

Perino also isn't saying when an accord might be reached.

The Iraqis have sought a timeline for U.S. withdrawal, but the administration speaks of a flexible time "horizon."

The two sides are so far apart that the goal now is for an interim deal, so that President Bush's successor can sort out the toughest issues left.