The nation’s most prominent federal watchdog, often credited with identifying potential taxpayer savings, may soon fall victim to steep government spending cuts.

The Government Accountability Office, the congressional investigative agency, stands to lose up to $50 million in funding this year that its defenders say would force widespread layoffs and the closure of its regional offices. Budget proposals also would force the agency to detail the costs and manpower used to publish each of its reports, a task that supportive lawmakers fear could politicize the nonpartisan office.

The GAO publishes more than 1,000 reports and audits annually, and agency officials frequently testify before congressional committees to detail their findings. Despite a relatively spot-free reputation and its work identifying billions of dollars in potential savings in recent years, House and Senate appropriators responsible for drafting the legislative branch budget seem determined to force the GAO to scale back as part of a 5.2 percent drop in congressional spending.

With lawmakers looking for cuts in all corners of the federal government, “the buck shrinks here,” Sen. Ben Nelson (D-Neb.), chairman of the Senate appropriations subcommittee on the legislative branch, said recently, adding later that his proposed cuts “are real and will force Congress and the agencies on Capitol Hill to live with less.”

Nelson’s proposed budget also would require the GAO to include detailed spending reports with each publication it releases that account for how many employees worked on the report, the total hours spent producing it and a tally of related travel expenses.

Those provisions infuriate several senators, especially Sen. Tom Coburn (R-Okla.), a frequent critic of government spending who often relies on the GAO to help him root out cases of waste, fraud and abuse.

Requiring detailed spending reports would “be an overly burdensome mandate that would further consume GAO’s dwindling resources without providing any obvious cost benefit,” Coburn and four colleagues wrote last week in a letter sent to Nelson’s subcommittee. No other congressional office — including the Congressional Research Service, which also publishes thousands of reports — is required to provide detailed spending totals, they said.

In a separate plea, Sens. Joseph I. Lieberman (I-Conn.) and Susan Collins (R-Maine) asked Nelson to drop plans for detailed spending reports, arguing that they could result in “a politicization of the GAO report process as members and committees are criticized for spending money on a GAO analysis.” Lieberman and Collins, the chairman and ranking Republican on the Senate Homeland Security and Governmental Affairs Committee, favor requiring the GAO to conduct one annual spending analysis of its work.

GAO officials declined to comment on the ongoing budget fight but said the agency is offering buyouts and early retirement offers to long-serving employees; 37 have accepted the offers, a spokesman said. Agency officials said they began offering the buyouts and early retirement offers before the budget debate began.