Top congressional Republicans hunted for support Thursday from pivotal moderate senators for a retooled House-Senate budget deal that could pave the way for passage this year of up to $550 billion in tax cuts through 2013.

GOP leaders reshaped their plan a day after the Senate parliamentarian ruled that under their initial budget, it would take 60 Senate votes — a virtually insurmountable margin for Republicans — for future tax cuts exceeding $350 billion. President Bush wants $726 billion in cuts, including eliminating individuals' taxes on corporate dividends and accelerating scheduled income tax reductions.

"It's looking good," House Majority Leader Tom DeLay, R-Texas, said about GOP efforts to craft a deal that could clear Congress.

The search for a budget deal came as lawmakers also tried reaching a House-Senate compromise on a near $80 billion measure paying the first bills for the Iraq war and other U.S. efforts against terrorism. GOP leaders hope to push both measures through Congress by Friday, when lawmakers are scheduled to begin a two-week spring break.

The leaders of both GOP-controlled chambers, however, have been focused on passing a final $2.2 trillion budget for 2004. Republicans want the measure to embrace as much of Bush's tax cut as possible, arguing that his plan would give the flagging economy a jolt.

Underscoring GOP frustration, Sen. Trent Lott, R-Miss., said Republicans believed Senate parliamentarian Alan Frumin "shifted positions ... in what appears to be under pressure" after earlier telling GOP aides his ruling would be favorable to them.

"You know what happened to the last parliamentarian who did that. I fired him," he said.

When he was Senate majority leader in 2001, Lott fired parliamentarian Robert Dove following budget rulings that went against the GOP. Lott replaced him with Frumin, parliamentarian when the Senate was under Democratic control.

Jay Carson, spokesman for Senate Minority Leader Tom Daschle, D-S.D., said Democrats had "absolutely not" pressured Frumin and that both parties had simply made their case to him.

Congress' budget sets revenue and spending totals for the year, but can also give later tax cut bills procedural protections so they need only 51 votes to pass the 100-member Senate. They otherwise could need 60 votes to prevail over opposition Democrats, who say the cuts would only deepen budget deficits beyond the record $300 billion-plus annual shortfalls now expected.

Despite the importance of Bush's tax plan to his agenda, Senate Republicans have only been able to muster 48 votes — including one Democrat — for tax cuts exceeding $350 billion.

Their keys to success would be winning the votes of moderate GOP Sens. George Voinovich of Ohio and Olympia Snowe of Maine, with Vice President Dick Cheney providing the tie-breaking 51st vote. By afternoon, it was unclear whether the pair would support the plan.

Under a new GOP proposal Thursday evening, the Senate's first tax bill would need 60 votes to exceed $350 billion. The House's could be $550 billion.

But the later House-Senate compromise would need only 51 votes for a price tag of up to $550 billion. That would give moderates in the narrowly divided Senate the ability to block anything they consider too big, yet also give the White House and GOP leaders many weeks to win them over.

"Our intent is to get it done," House Speaker Dennis Hastert, R-Ill., said of GOP efforts to finalize a budget agreement.

As for the rest of the compromise budget, it would bow to demands from moderates by dropping the $265 billion in savings over 10 years that the House-passed plan had ordered in benefit programs such as student aid and Medicaid. It would allow roughly the same $787 billion in spending next year for annually approved, nonbenefit programs that Bush had proposed, and claims to be balanced in 2012.

The last, testy disputes between the two chambers over the war spending bill included House demands that the Senate drop hundreds of millions of dollars that senators added. These included $50 million to help the U.S. shipbuilding industry, a provision helping catfish producers share in emergency farm aid approved months ago, and a provision removing some southern Nevada dairies from a federal system that requires them to pay higher prices for milk.

"I'm just sorry we repealed the law on dueling. I'd have shot a couple of the sons of bitches," Senate Appropriations Committee Chairman Ted Stevens, R-Alaska, joked to reporters on Wednesday regarding an earlier bargaining session with the House.