The measure, which passed 99-0, would bring the total cost of combat and reconstruction past $300 billion.
The House and Senate versions would give President Bush much of the money he has requested but differ over what portion should go to military operations versus other assistance, according to the Associated Press.
The Pentagon has said it needs the funding by the first week in May, so House and Senate negotiators are expected to work quickly to marry the two bills and present a final version for the president's signature.
Meanwhile in Iraq, a commercial helicopter contracted by the U.S. government was shot down by missile fire 12 miles north of Baghdad, killing six American contractors and at least five others, reported the AP.
Bulgaria's Defense Ministry said the Mi-8 helicopter was downed by missile fire and the victims included a three-person Bulgarian crew.
The six Americans worked for security contractor Blackwater USA, the U.S. Embassy said. The North Carolina-based contracting firm provides security for State Department officials in Iraq.
Last year, four Blackwater employees were killed in Fallujah, and their bodies burned and mutilated. Two of the corpses were stung up on a bridge over the Euphrates River.
The helicopter in Thursday's crash was owned by Bulgaria-based Heli Air and chartered by Toronto-based SkyLink Aviation Inc. Television footage showed burning wreckage and personal belongings scattered over a wide area.
Paul Greenaway, SkyLink air operations manager, said the Americans were "doing some sort of security work," and the helicopter was on its way to Tikrit, according to the AP. He said the victims also included two security guards from Fiji.
In a separate incident, a roadside bomb killed another Blackwater employee in Ramadi, west of Baghdad, and wounded four others, said a spokesman for Blackwater USA, reported CNN.
The incidents came a day after Iraq's interim Prime Minister Iyad Allawi escaped an assassination attempt. His convoy was targeted by a suicide car bombing, which killed several security guards and policemen at a checkpoint.
Several Islamist Web sites posted statements from the Iraq branch of al-Qaida, claiming responsibility for the attack.
-- Compiled from wire reports and other media sources