As centrist Senate lawmakers planned a budget deal that would reduce President Bush's $726 billion tax cutting package by half, other legislators said Tuesday they would accept no more cuts until they received estimates on the costs of war against Iraq.

"I cannot in good conscience vote in favor of tax cuts, irrespective of their size or to which segment of the population they are targeted. Nor can I support any substantial spending increases that are not related to improving our nation’s defense from the obvious and serious threats facing us today," said Sen. John McCain, R-Ariz.

McCain said that he would later support stimulating the economy through moderate tax cuts like payroll tax relief, "but not at this time."

Sen. Kent Conrad, D-N.D., ranking member of the Budget Committee, said he would offer an amendment that would prohibit considering legislation that would increase the deficit until the president submits to Congress an estimated cost of the war.

"In the past — Second World War, First World War — Uncle Sam delivered a message to the American people. It takes taxes and bonds. And the message was that it takes common sacrifice to defend this nation. But that's not what this budget says. ... That strikes many of us as unwise," Conrad said.

Republican leaders supporting the president's proposal planned on bringing a budget vote as early as Tuesday, saying they would try to resist cutting the president's plan to $350 billion in cuts through 2013.

"I'd like to have the president's number. I'll defend the president's number on the floor," Senate Budget Committee Chairman Don Nickles, R-Okla., told reporters after GOP senators held a closed-door strategy session.

But several Democrats aren't even willing to support limited tax cuts and some senators worried that there would not be enough votes to reduce the tax cut at all.

Centrist Republicans said if they do get a smaller tax cut, they would like to put the saved money toward bringing down the deficit, rather than greater spending.

Sen. George Voinovich, R-Ohio, said he would redraft the president's proposal to require that any money saved by making the tax cut smaller be used to reduce budget deficits.

Conrad has said he expects the deficit to reach $500 billion of the $2.2 trillion budget for next year.

"We certainly don't want the balance between what we did and what's in the budget to be spent," Voinovich said.

The debate as crafted by Senate GOP leaders precludes any chance of filibuster of the president's plan, but the budget as a whole has a long way to go before passage. Among the president's priorities, drilling in Alaska's Arctic National Wildlife Refuge may fall by the wayside.

Sen. Ted Stevens, R-Alaska, a chief supporter of the proposal, has said he lacks the 50 votes necessary to keep the language in the budget, said one Republican, speaking on condition of anonymity. Stevens spokeswoman Melanie Alvord said the senator did not know how many votes he has, but last week GOP sources said supporters were one vote shy.

The House and Senate are hoping to wrap up the budget blueprints this week. The bill, when completed by the two chambers, will set overall limits on revenues and expenditures, with changes to be enacted in separate bills later. It does not need the president's signature.

House and Senate Republicans have already agreed to put on hold the rest of the president's proposed $1.57 trillion in tax cuts, saying they can get to them in later years.

The White House said it would submit a price tag for the cost of fighting Iraq within days of the start of the war. That bill, expected to be as much as $90 billion, including money for domestic security and aid to Israel, could arrive on Capitol Hill as early as Friday, congressional aides said.

The Associated Press contributed to this report.