A liberal Democrat's attempt to impose quick U.S. troop withdrawals from Iraq collapsed in the U.S. Senate, as expected, but leaders on Thursday insisted they will retool legislation and force votes in coming months.

The Senate spent much of this week debating a plan by Sen. Russ Feingold of Wisconsin to begin withdrawing most American troops from Iraq by July.

His effort, like one last December, faced deep opposition in the chamber, where members have repeatedly blocked steps to impose timetables for winding down a war that is entering its sixth year.

Senate leaders pulled the bill from debate when it was obvious there was not support for passage.

"We'll be back. There are a number of things we're considering," Senate Majority Leader Harry Reid, a Nevada Democrat, told reporters in acknowledging Feingold's measure was doomed.

In a month or so, Congress is expected to begin debating President George W. Bush's request for more money for the Iraq and Afghanistan wars. In the past, Democrats have tried to tie conditions to the funds, including withdrawal timetables.

The next congressional debate on the Iraq war could come in April or May as the U.S. presidential campaigns intensify.