An amendment cutting Bush's Iraq request by $1.9 billion to pay for new Border Patrol agents, aircraft and some fencing at border crossings widely used by illegal immigrants was adopted on a 59-39 vote.
While the border security funds had sweeping support, Democrats and Republicans argued over whether the cuts to Pentagon war funds would harm troops on the ground in Iraq. The cuts, offered by Judd Gregg, R-N.H., trim Bush's request for the war by almost 3 percent but don't specify how.
The vote came in the wake of a toughly worded promise by the White House to veto the $106.5 billion measure unless it is cut back to below $95 billion.
Sen. Hillary Clinton, D-N.Y., said Gregg's cuts would "take money from troop pay, body armor and even joint improvised explosive device defeat fund. Now that is a false choice and it is a wrong choice."
Gregg responded heatedly, arguing that the cuts eventually would come from other parts of the massive Pentagon budget rather than U.S. forces in Iraq.
"To come down here and allege that these funds are going to come out of the needs of the people on the front lines in Iraq or Afghanistan is pure poppycock," he said.
In its veto statement, the White House said the bill contains too many items that are "unrelated to the war or emergency hurricane relief needs." It said a final House-Senate compromise on it "must remain focused on addressing urgent national priorities while maintaining fiscal discipline."
The move is likely to force senators to drop most of their $14 billion in add-ons for farm aid, highway repairs, aid to the Gulf Coast fishing industry and other projects. The additional money had won the ire of the White House and GOP congressional leaders and scorn from conservatives allies whose support is crucial on Election Day.
The bill is sure to be carved back in House-Senate negotiations next month, and Bush may very well not have to follow through on his veto promise.
The White House statement said farm aid in the bill is unnecessary after a booming 2005 crop year and that a controversial $700 million relocation of a Mississippi freight rail line would unfairly put taxpayers on the hook for privately owned infrastructure.
To accommodate the White House's objections would require the Senate to shed numerous projects. That would represent a departure a disaster aid bill was handled in December, when Congress added $12 billion in new spending not requested by Bush.
Even as the White House raised the potential of a first-ever Bush veto, the administration on Tuesday asked the Senate for $2.2 billion more to repair and strengthen levees in and around New Orleans. The request wouldn't add to the overall cost of the bill since it was accompanied by a decrease in Federal Emergency Management Agency disaster funds.
The White House acknowledges that FEMA coffers would have to be replenished again in the fall instead of next year under the proposal.
Bush insists that total spending in the bill be capped at his $92.2 billion request for Iraq and hurricane relief, though he is willing to accept $2.3 billion in the bill to prevent an outbreak of avian flu. His February budget anticipated the funding, but the White House has been slow to follow up with a detailed request.
Gregg chairs the Appropriations Homeland Security Subcommittee. His border security plan focuses used on the capital needs of the Border Patrol and the Coast Guard, including new planes, helicopters, ships, communications equipment and a project to build a fence along the Mexico border near San Diego. CBS News correspondent Bob Fuss reports the measure is designed in part to build support among conservatives for a major immigration bill.
Gregg said his plan would "give the people who are defending us on our borders, the border security agents, the Custom agents, the Coast Guard, the tools they need to do their job right — the unmanned vehicles, the cars, the helicopters which are a critical part of our fight in the war on terrorism. It has to be done now."
The underlying bill contains $67.6 billion for Pentagon war operations and $27.1 billion for hurricane relief, including grants to states to build and repair housing and $2.1 billion for levees and flood control projects. The funding for hurricane relief exceeds Bush's request by $7.4 billion.
To date, Congress has provided about $315 billion for the war in Iraq and anti-terror spending since September 2001.