WASHINGTON – White House officials and Congress’ top budget writers tried rallying support Tuesday for President Bush’s $2.57 trillion budget, but cracks in Republican unity showed as lawmakers digested the plan’s proposed spending cuts.

“Stay in the game the rest of the year,” House Budget Committee Chairman Jim Nussle, R-Iowa, urged colleagues who have voiced support for paring the deficit since the budget’s release Monday. “Don’t claim you want to cut the deficit in one breath and demand we spend more in the next.”

Joshua Bolten, Bush’s budget chief, told Nussle’s committee that the president “won’t hesitate” to veto excessive spending bills – which he has yet to do in four years.

Even so, Republicans across the Capitol flashed signs of concern about Bush’s proposals, raising questions about how closely the GOP-led Congress will follow the president’s fiscal outline.

“Maybe some things the president doesn’t want to keep we’ll put back in,” said Sen. Ted Stevens, R-Alaska, a top member of the Senate Appropriations Committee. “But I think we’ll keep the budget discipline.”

Underscoring GOP fault lines, Senate Budget Committee Chairman Judd Gregg, R-N.H., opened Tuesday’s Senate session by voicing support for Bush’s plan. Gregg said that cuts were so broadly aimed that it “gores everybody’s ox.” But that didn’t blunt the pain for some lawmakers.

“Some are very drastic,” Sen. Olympia Snowe, R-Maine, said in an interview of Bush’s planned cuts for education, child care and home-heating aid. “There should have been a more balanced approach in these areas.”