Bickering over budget cuts slowed progress on Senate legislation needed to prevent a shutdown of the U.S. federal government, raising a new obstacle just as Washington's gridlock appeared to have eased.
Congress had been poised to pass a bipartisan funding bill to clean up its unfinished business for the long-underway 2013 budget year, but a dispute arose in the Senate over cutbacks that threaten to shut down dozens of smaller airport control towers.
The latest test of wills emerged as Republicans and Democrats in Congress struggled with two goals _ ensuring there is no interruption of routine government funding while trying to ease the impact of $85 billion in across-the-board spending cuts that kicked in earlier this month.
Sen. Jerry Moran, a Republican, refused repeatedly to permit final passage of the catchall spending bill unless Democrats first vote on his plan for erasing most of the cuts aimed at the towers. Senate Majority Leader Harry Reid, a Democrat, just as persistently declined to give in, and other Democrats noted that House Republicans had rejected calls to give all federal agencies the same type of budget flexibility.
The Republican-held House of Representatives has already passed its own version of the spending measure, and had been expected to quickly clear the Senate legislation and ship it to President Barack Obama for his signature.
Even if the bipartisan funding bill passes, it would merely end the fight over the annual spending bill required to fund federal government operations. That would allow Congress to turn away from the current budget year and resume partisan battling over future spending.
The House of Representatives and Senate are gearing up for votes this week on sharply different budget blueprints for next year and beyond. The annual ritual is meant to lay out each party's stance on federal spending.
The rival House and Senate budgets for the future are party-defining documents that won't become law as written, with Washington as divided as ever over how to rein in deficit spending without hurting the economy.
The House budget measure promises a balanced budget by the end of a decade with spending cuts alone. The Senate budget would mix spending cuts and tax hikes. It would leave significantly larger deficits but stabilize the national debt as a share of the economy, a measure that economists say is essential to avoiding a debt crisis like Greece and other European nations have experienced.
The U.S. debt is now at $16.6 trillion. The Treasury Department has indicated that the annual deficit, at least, is starting to shrink. Higher taxes and an improving economy are expected to hold the deficit below $1 trillion for the first time since Obama took office.
Budget negotiations have been complicated by the $85 billion in annual across-the-board spending cuts that are slamming both the military and domestic agencies.
The automatic budget cuts _ the so-called sequester _ were designed to be so crude that they would force both sides to reach a long-term spending agreement. But no deal was reached and they were triggered on March 1.
The spending cuts are set to continue through the decade, leaving the government with no flexibility in implementing them. Both parties agree that is bad policy.
Despite Washington's failure to reach a lasting deal, Obama hasn't given up on a so-called grand bargain. The president has continued talks with Republicans, even making a rare visit last week to Congress.
Obama has indicated he is willing to reduce spending on big entitlement programs such as Social Security payments to retirees and the Medicare and Medicaid programs that provide health care coverage to the elderly and poor _ traditionally a taboo among Democrats _ in exchange for raising taxes by closing loopholes in the tax code.
Republicans oppose any more tax increases. They say Democrats got their way with hikes on the wealthy in the New Year's Day "fiscal cliff" deal that prevented income tax increases for all but the wealthiest Americans.
Associated Press writers David Espo and Andrew Taylor contributed to this report.