Senate procedures helped Republicans derail this year's defense bill Friday, as the chamber voted to oppose any last-minute spending added by Democrats for anti-terrorism spending.

Though the vote doesn't mean the end of the $318 billion defense measure, it does mean Democrats will have to reconsider the homeland security priorities they had attached to it. The spending plan was their response to the Sept. 11 attacks.

In the 50-50 vote, Republicans, along with Sen. Russell Feingold, D-Wis., were able to deny Democrats the 60 votes they needed to add billions more to the bill than was agreed upon between the president and congressional budget negotiators in October.

The rally enabled Republicans send a victory to President Bush, who had threatened to veto the entire defense measure if anti-terror spending exceeded $20 billion.

Realizing that defeat was probable, Senate Majority Leader Tom Daschle, D-S.D., told reporters that Democrats would offer an alternative $20 billion package, the size Bush has demanded. Aides said it would provide more money for New York and fighting bioterrorism than the president has proposed.

Asked about the Democrats' willingness to limit spending to $20 billion, Senate Minority Leader Trent Lott, R-Miss., said, "If it is, that would be a major step forward."

The Senate now turns to the bill passed by the GOP-led House. It offers more than the president's plan for New York, bioterrorism and food safety, but less than the Democrats' plan for defense, federal law enforcement and border security.

The fate of that bill is uncertain, but what is certain is that Daschle and Democrats miscalculated their attempts to paint their rivals as being opposed to increased domestic security in the wake of Sept. 11 attacks.

Lashing out on the floor right before the vote, Sen, Robert Byrd, D-W.Va., sponsor of the Democratic package, said, "This vote sends the message that it's more important to win a political battle than it is to win the war against terrorism." 

But the White House, hoping to cap spending on a year that had seen wildly unexpected expenses, countered that if more money is needed, than the president will ask for it next year.

In a letter to congressional leaders voicing Bush's veto threat, administration officials said that through November, only $6 billion has been spent of the $40 billion allocated by Congress three days after the attacks.

Of that money, Bush was given control of half of it and lawmakers must vote on the details of the second $20 billion, which was attached to the defense bill.

Republicans said the Democratic proposal for $8 billion more than Bush proposed in emergency aid to New York and other places the terrorists hit was not necessary because recovery costs remain unknown. They said the Democrats' $237 million plan for local law enforcement aid "will have little or no tangible impact on preventing or responding to terrorism."

The Associated Press contributed to this report.