The Democrats, in a 50-48 vote largely along party lines, thwarted a Republican attempt to erase a U.S. withdrawal date attached to the proposed spending bill for the wars in Iraq and Afghanistan.

Hawai'i's two senators, Daniel Inouye and Daniel Akaka, both Democrats, voted in support of the withdrawal of combat troops.

The move paves the way for a proposal that directs the president to begin the withdrawal of U.S. forces from Iraq within 120 days of its enactment. It also sets the non-binding goal of having only a limited number of U.S. troops in Iraq by March 31, 2008.

The legislation is expected to be voted on as early as Wednesday. If it passes, as expected, both chambers of Congress would be on record calling on the Bush administration to wind down the war in Iraq by next year.

The Democrats, while holding a narrow majority in the Senate, needed the help of maverick Sen. Chuck Hagel, R-Neb., to overcome votes by Sens. Mark Pryor, D-Ark, and Sen. Joseph Lieberman, I-Conn., who voted with the Republicans to remove the troop withdrawal language from the bill.

The withdrawal language is tied to a $122 billion spending bill to fund the two wars. With the president's threat to veto the measure, the Democratic leadership and White House could find themselves in politically vulnerable positions because Defense Secretary Robert Gates has warned that current funding for the Iraq war will dry up in a matter of weeks.

After today's vote, Senate Majority Leader Harry Reid, D-Nev., played his cards close to his vest on how much he is willing to slash from the legislation.

"I hope he (Bush) will work with us so we can come up with something agreeable for both" sides, Reid said at a news conference. "But I'm not anxious to strip anything out of the bill."

Before the vote, White House spokeswoman Dana Perino said, "This and other provisions would place freedom and democracy in Iraq at grave risk, embolden our enemies and undercut the administration's plans to develop the Iraqi economy. If this legislation were presented to the president, he would veto the bill."

The Senate action comes on the heels of the House voting last week for a war spending bill that called for the pullout of all combat troops by the fall of 2008. The Senate and House will have to craft compromise language before it is passed and sent to Bush for his signature, or the more likely prospect of a veto.

With a slim majority in the Senate, the Democrats needed the vote of Hagel, a Vietnam veteran who has been critical of the president's handling of the war.

Hagel and Sen. James Webb, D-Va., also introduced an amendment to the legislation today that would limit the amount of time troops could be deployed overseas as well as calling for troops that are deployed to be certified "mission capable" before they could be dispatched to a war zone. The Senate may vote on the Hagel-Webb proposal Wednesday.

"It's now time," Hagel said, "for the Congress to step forward and establish responsible boundaries and conditions for our continued involvement in Iraq."

Republicans prevented debate earlier this year on non-binding measures critical of Bush's decision to deploy additional troops to Baghdad and the Anbar province as part of the administration's so-called troop surge. And just two weeks ago, the Democrats failed to win a vote that would have set a similar timeline for withdrawal.

In that vote, Sen. Ben Nelson, D-Neb., voted with the Republicans, but this time he stayed with his party after it agreed to endorse specific benchmarks for the Iraqi government to fulfill.

"I do not support setting a calendar date for withdrawal from Iraq," Nelson said in a statement. "However, the legislation also laid out benchmarks and required regular briefings to Congress. Setting measurable goals is absolutely essential for our strategy in Iraq and I have been pushing for these conditions for staying for more than two years."

Senate Republicans could have blocked the vote by filibuster, as they did with the non-binding resolution critical of the president's troop buildup. Instead, Senate Minority Leader Mitch McConnell, R-Ky., allowed the debate to go on, effectively putting the onus on the Democrats and the president.

In recent weeks, mounting public discontent has manifested itself, with several polls showing that more Americans are wary of the Bush administration's handling of the Iraq war. The Pew Research Center recently published a poll in which 59 percent of those polled wanted their congressional representatives to support a U.S. withdrawal from Iraq by the end of August 2008, the deadline set in the House version of the spending bill, which passed by a 218-212 vote on Friday.

In Lieberman's floor speech, he made note of the polls and opponents' argument that U.S. troops have no place mediating a civil war. But he noted that U.S. troops did exactly that in Bosnia and Kosovo.

He went on to say that proponents of a deadline are proposing to "snatch defeat from the jaws of progress" in Iraq.

"It has never been easier to advocate a withdrawal, but I cannot support it because I believe deeply it would be wrong," Lieberman said.

McConnell and other Republicans argued that setting a timeline was equivalent to setting a "surrender date" and would aid the enemy in its plan to destabilize Iraq.

"Setting a date for withdrawal is like sending a memo to our enemies that tells them to rest, refit and re-plan until the day we leave," McConnell said. "It's a memo to our friends, too, telling them we plan to walk away and leave them on their own, regardless of what we leave behind."

But Democrats argued passionately that they would be derelict in their duty if they didn't push for a new policy.