Top Republicans tried to determine Monday whether they can keep Democrats and GOP moderates from slicing President Bush's tax-cutting economic plan in half as the Senate began debating a $2.2 trillion budget for next year.

At stake was Bush's high-profile proposal to eliminate the levy on corporate dividends and make other tax reductions, at a cost of $726 billion through 2013. With federal deficits climbing toward record levels, and a potentially costly war with Iraq looming, a combination of Democrats and centrist GOP senators had a good chance of pushing the price tag down to $350 billion.

"Let's vote, then let's decide how much money we're going to spend" on the growth package, said Senate Budget Committee Chairman Don Nickles, R-Okla., a staunch advocate of Bush's plan.

Republicans were debating internally what to do if they lacked the votes to keep the $726 billion in tax reductions intact. Worried that money would be shunted toward spending, Republicans were considering reducing the tax cuts on their own if they could strike a deal with both parties' moderates to limit extra spending that would result, GOP aides said.

Also in jeopardy was a budget provision that would allow oil drilling to begin in Alaska's Arctic National Wildlife Refuge, another of Bush's top domestic goals.

Sen. Ted Stevens, R-Alaska, a chief supporter of the proposal, has said he believes he lacks the 50 votes necessary to keep the language in the budget, one Republican said, 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.

Republicans were hoping to push tax and spending blueprints through both the House and Senate this week. The budget, when the two chambers complete a compromise, will sets overall limits on revenues and expenditures, with changes to be enacted in separate bills later. It does not need the president's signature.

Overall, the House and Senate budgets would make room for most of Bush's proposed $1.57 trillion in tax cuts over the coming decade, though some form of the economic package is the only portion likely to become law this year.

Democrats said war and annual federal deficits projected to exceed $300 billion made the GOP's tax cuts far too large and ill-timed.

"It disturbs me we are even considering a massive tax-cut package at a time when we are on the brink of war," said Sen. Kent Conrad of North Dakota, the Senate Budget panel's top Democrat. "I don't think it sends the proper message at a time when our troops are on the field" and ready to make sacrifices.

Neither the House nor the Senate budgets includes money for a military confrontation with Iraqi President Saddam Hussein, which could cost $100 billion or more for combat plus a postwar U.S. occupation and rebuilding effort.

In the House, GOP moderates were complaining that in order to make room for Bush's tax cut, the budget would have to cut spending too deeply. That left House Republican leaders scrambling to learn whether they had the votes to push the fiscal framework to passage without changing it first.

One possibility was that House leaders might have to scale back some of the spending reductions their budget proposals.

GOP leaders claim their Senate plan would revive balanced budgets by 2013, the House proposal by 2010.

The Alaska oil-drilling language in the Senate budget would prevent opponents from stopping the drilling with a filibuster, a Senate delay that would force supporters to win 60 of the Senate's 100 votes to prevail.