President Bush has dug out a rarely entertained executive privilege — a veto stamp that he said he is willing to use for the first time since taking office to curb spending Congress has proposed in the name of terror response.

The threat, reinforced Wednesday by the White House, seems to have had its intended effect on Republicans. But it does not seem to be resonating with Democrats who are planning ways to spend billions of dollars to beef up the FBI, improve the transportation infrastructure and guarantee health care for laid-off workers, among other things.

"If he wants to veto homeland defense; if he wants to veto a bill that provides vaccines for small pox; if he wants to veto a bill that provides antibiotics for anthrax; if he wants to veto a bill that protects us against terrorists slipping across the borders to destroy our bridges, to destroy our nuclear plants, to destroy our military facilities in this; if he wants to veto a bill like that let him go to it," railed Senate Appropriations Committee Chairman Robert Byrd, D-W.Va. "But he's going to have to explain to the American people his failure to sign it."

Bush may be in a good position to do so. With 84 percent approval ratings, he plans to speak to Americans Thursday in a prime-time address about the war on terror, an opportunity for him to plead his case for restraint.

He also may argue that no emergency requires Congress to appropriate more money than it can spend.

In the two months since the terror attacks, Congress has only managed to spend $3.9 billion of the $40 billion in emergency relief approved immediately following Sept. 11.

"They can't even spend what has been approved fast enough because that is the way money flows in reality. So if Congress were to put an additional $20 billion on there, it is just more money that cannot yet be spent," said White House press secretary Ari Fleischer.

Fleischer said the president wants Congress live up to an agreement the two sides reached in September on discretionary spending yet to be passed by Congress for the fiscal year that began Oct. 1.

The $686 billion agreement is separate from the $40 billion in emergency spending and another $15 billion for an airline bailout following the terror attacks, and $90 billion more than last year's budget.

"The president believes very strongly that the amount of money that has been set aside per an agreement made with members of Congress ... is ample funding to fulfill the government's mission to protect the nation and to protect people both internationally and at home," Fleischer said.

The president also has agreed in principle to an economic stimulus plan. The House passed a $100 billion measure three weeks ago. The Senate is deadlocked on the House measure supported by Republicans and a Democratic alternative.

The Republican bill offers tax breaks to businesses, including a repeal of the alternative minimum tax and accelerated depreciation to encourage capital purchases. It also offers aid to states to extend unemployment benefits and a tax rebate to low-income workers.

Democrats say the bill needs to add more money for unemployment and health insurance for laid-off workers. Neither side will budge.

Whatever the final plan, Congress' wish list is up to $400 billion and counting, according to Citizens Against Government Waste.

Fleischer said the president would be willing to approve emergency supplementals in the coming year as needed. But congressional leaders, trying to plan their winter recess, argue that circumstances demand fast action.

"We come back in January, but it's usually later in January. By the time you get the bill put together, you could have a lot of further disagreement about what ought to be in the bill," House Minority Leader Dick Gephardt, D-Mo., said. "It probably will be four months before we can actually enact new legislation. Why not put it in place?"

Byrd made his own threat to do just that. He said he is going to attach a $20 billion domestic security plan to this year's defense spending bill, a bill the president desperately needs passed to continue a war on terror that is costing the military approximately $1.2 billion per day.

"The last train out of the station will be the defense appropriations bill, and so if all else fails then I intend to attempt to put this homeland security bill on the last appropriations bill," Byrd said.

Sharon Kehnemui is a digital marketing consultant and founder of Frequency Partners. She is a former senior politics editor for FoxNews.com. Follow her on Twitter @digisharon.