The U.S. Senate gave on Thursday final approval to a war spending bill that requires troop withdrawal from Iraq to begin by Oct. 1, with a goal of ending U.S. combat operations there by next March.

U.S. President George W. Bush has repeatedly pledged to veto the bill and White House spokeswoman Dana Perino promised Thursday morning that he will act "very soon."

According to congressional voting records, the Senate approved the measure by a 51-46 vote, a day after the House passed the bill by 218-208.

"It's time to end the loss of American lives and to begin to bring our soldiers home," Democratic Sen. Edward M. Kennedy said on Senator floor.

"For the sake of our troops we cannot repeat the mistakes of Vietnam and allow this to drag on long after the American people know it's a mistake," he said.

The 124.2 billion-U.S. dollar bill, a compromised version agreed by House and Senate negotiators earlier this week, is now poised to reach Bush's desk by early next week after clearing its way in the congress.

Last month, both the House and Senate have attached language to their respective version of the war funding bill calling for U.S. combat troops to leave Iraq in 2008 -- the House by the end of August, the Senate by March of that year.

The original House version of the bill had set a firm date for withdrawal.

However, the compromise measure the House endorsed Wednesday is somewhat weaker in that respect, in order to boost its chance to win more support in the congress.

Bush has repeatedly said he will veto any bill with a timetable to withdraw troops from Iraq.

If he vetoes the bill, which looks certain, the congress will need a two-third majority to overthrow the veto.

Otherwise, the congress will have to draft a new funding bill and send to Bush again.

With neither side willing to back down, an impasse will be a certainty.