The Senate cleared the measure by an overwhelming 91-9 vote that gives the GOP an early but modest victory in its drive to rein in government. Obama has until Friday to sign the measure and keep federal offices open and operations intact. The House passed the legislation on Tuesday.
The measure buys time for Obama, the GOP-dominated House and the Democratic-led Senate to start talks on legislation to fund the government through the end of September.
House Republicans last month muscled through a measure cutting this year's budget by more than $60 billion, while trying to block implementation of Obama's health care law and a host of environmental regulations. The White House has promised a veto and it will take weeks or months to negotiate a compromise funding measure that Obama would sign.
The $4 billion in savings comes from some of the easiest spending cuts for Congress to make, hitting accounts that Obama already has proposed eliminating and reaping some of the money saved by earlier moves by Republicans to ban lawmakers from "earmarking" pet projects for their districts and states.
"Our priorities are twofold. One, keep the government running so essential services don't get interrupted," said Senate Majority leader Harry Reid, D-Nev. "Equally important, we need to lay the groundwork with a budget that keeps what works and cuts what doesn't."
"While some have been patting themselves on the back for proposing $4 billion in so-called 'cuts,' in reality, this bill fully funds billions upon billions of dollars in wasteful, duplicative programs that should be eliminated, reduced, or reformed," said freshman GOP Sen. Mike Lee of Utah.
But other Republicans seized on the vote as setting a precedent for cuts of $2 billion a week - which, if extended through the end of the budget year, would match the $61 billion in cuts in a measure passed by the House last month to meet their promise of cutting federal agency operating budgets back to levels in place before Obama took office.
"It's hard to believe when we're spending $1.6 trillion more than we're taking in a single year, that it would take this long to cut a penny in spending, but it's progress nonetheless," said Senate GOP leader Mitch McConnell of Kentucky. "It's encouraging that the White House and congressional Democrats now agree that the status quo won't work, that the bills we pass must include spending reductions."
The White House has promised a veto of the bigger GOP measure, citing crippling cuts to many federal agencies and studies by economists that predict the spending cuts would harm the economy.
The GOP won control of the House and gained seats in the Senate last fall with the backing of tea party activists demanding deep, immediate cuts in federal spending. They say that an early down payment on those cuts would send a confidence-building signal to financial markets and the business community.
Still, difficult negotiations loom between House Republicans, Senate Democrats and the White House over the full-year spending measure. It blends cuts across hundreds of programs - education, the environment, homeland security and the IRS among them - with a slew of provisions that attack clean air and clean water regulations, family planning and other initiatives.