The Republican-controlled US House of Representatives has passed sweeping legislation to cut $61 billion (£37.5 billion) from hundreds of federal programmes and shelter coal companies, oil refiners and farmers from new government regulations.
The 235 to 189 vote to send the bill to the Senate was largely along party lines and defied a veto threat from President Barack Obama. It marked the most striking victory to date for the new Republicans elected last year on a promise to attack the deficit and reduce the reach of government. Three Republicans joined Democrats in opposing the measure.
"The American people have spoken. They demand that Washington stop its out-of-control spending now, not some time in the future," said new Republican congressman Tim Huelskamp.
The $1.2 trillion (£738.6 billion) bill covers every Cabinet agency until the September 30 end of the budget year, imposing severe spending cuts aimed at domestic programmes and foreign aid, including aid for schools, nutrition programs, environmental protection, and heating and housing subsidies for the poor.
But Senate Democrats promise higher spending levels and are poised to defend Obama's health care bill, environmental policies and new efforts to overhaul regulation of the financial services industry.
Changes rammed through the House will shield greenhouse-gas polluters and privately owned colleges from federal regulators, block a plan to clean up the Chesapeake Bay, and bar the government from shutting down mountain-top mines it believes will cause too much water pollution, siding with business groups over environmental activists and federal regulators in almost every instance.
The gulf between the two sides means difference over the measure will not be resolved in the short-term, requiring a temporary spending bill when a current stop-gap measure expires on March 4.
After four long days of debate, Republicans left their conservative stamp in other ways.
They took several swipes at the year-old health care law, including voting for a ban on federal funding for its implementation. At the behest of anti-abortion lawmakers, they called for an end to federal funding for Planned Parenthood.