A modest, bipartisan budget pact designed to avert another government shutdown and ease the harshest effects of automatic budget cuts is on the brink of passing the Senate.

The Democratic-led Senate is on track to clear the bill Wednesday for President Barack Obama's signature after a 67-33 vote Tuesday in which it easily hurdled the 60-vote threshold under Senate rules to close debate and advance the measure to a final vote. The budget bill easily passed the Republican-controlled House of Representatives last week.

The measure would restore $45 billion, half the amount scheduled to be automatically cut from the 2014 operating budgets of the Pentagon and some domestic agencies, lifting them above $1 trillion. An additional $18 billion for 2015 would provide enough relief to essentially freeze spending at those levels for the year.

The budget deal marks a modest accomplishment for the divided and often dysfunctional Congress. It comes at the end of a chaotic year punctuated by a 16-day partial government shutdown spurred by Republicans in a futile attempt to curb implementation of Obama's health care reform law, brinksmanship over raising the federal debt limit to avert a default by the U.S. Treasury, and congressional gridlock on issues ranging from immigration to gun control. All that has taken a toll on the approval ratings of both Republicans and Democrats — and Obama himself — creating anxiety across the political spectrum over next year's elections when control of Congress will be at stake.

The bill advanced Tuesday with the help of 12 Republicans, several of whom promised to oppose the measure in Wednesday's final vote because it fails to take on the nation's most pressing fiscal challenges. It would barely dent deficits that are predicted to lessen in the short term but grow larger by the end of the decade and into the next. Democrats supported the measure, even though many were unhappy that the measure lacked an extension of long-term unemployment benefits that are due to expire for nearly 1.3 million Americans on Dec. 28.

One provision, cutting the inflation increases of pensions for military retirees under the age of 62, was proving to be especially unpopular among members of both parties. Members of the military are eligible to retire after 20 years at half pay. The military pension cut was included in the bill at the direction of House Budget Committee Chairman Paul Ryan, who led the Republican side in the budget pact negotiations.

Top Democrats said they would revisit the cut, which raises $6 billion over 10 years, before it takes effect in two years. Senate Budget Committee Chairman Patty Murray. — Ryan's Democratic negotiating partner on the budget agreement — was grilled by Republican Sen. Roger Wicker on whether she knew the cut could reduce by $80,000 the lifetime benefit of a soldier who retires in his or her early 40s.

"I would suggest the senator ask that question to Chairman Ryan," Murray said. In a document defending the cut, Ryan's staff called pensions to middle-aged military retirees "an exceptionally generous benefit, often providing 40 years of pension payment in return for 20 years of service" and noted that "most begin a second career after leaving the military."

"This bipartisan bill takes the first steps toward rebuilding our broken budget process. And, hopefully, toward rebuilding our broken Congress," Murray said.

Democratic Sen. Jeanne Shaheen, who faces a potentially tough re-election campaign in New Hampshire next year, promptly announced she would seek to repeal the military pension cut. The proposed pension cut has drawn howls of protest from senators with large military presences in their states.

"I promise you this. If we don't fix it now, not only are we going to review it, we are going to fix it," Republican Sen. Lindsey Graham said. "How could any commander in chief sign a bill that does this?"

Shaheen was joined by more than a dozen other Democrats in announcing legislation to restore the military retirement benefits and make up the money by closing a tax loophole on offshore corporations.

The budget pact sets the stage in January for the pragmatic-minded House and Senate Appropriations committees to draft a trillion-dollar-plus omnibus spending bill combining the 12 annual appropriations bills for the budget year that began Oct. 1. It would provide $1.012 trillion for the fiscal 2014 year already under way, a $45 billion increase over what would be required under the penalty imposed by a 2011 budget deal.

Agency budgets totaled $986 billion in 2013 after automatic cuts called sequestration were imposed, causing numerous furloughs, harming military readiness and cutting grants to local school districts, health researchers and providers of preschool care to low-income children, among numerous effects.

Due to the design of the automatic cuts, even with the boost the Pentagon still would see its non-war 2014 budget essentially frozen at 2013 levels, while domestic agencies would see an increase of about 4 percent. But those levels remain well below what was envisioned in the 2011 budget pact.

The cuts would be replaced with money from things such as higher airline security fees, a requirement that new federal workers pay more toward their pensions, the 1-percentage-point cut in the pensions of working-age military retirees and premium increases on companies whose pension plans are insured by the federal government.

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