Defense Secretary Chuck Hagel speaks during a joint press conference with Philip Hammond, Britain’s secretary of state for defence, following meetings at the Pentagon in Washington, D.C., on May 2, 2013. (Saul Loeb/AFP/Getty Images)

The Pentagon is likely to face steep, across-the-board budget cuts beyond the end of this fiscal year, the two top lawmakers on the Senate Armed Services Committee warned on Friday, as they asked the secretary of defense to lay out in detail the consequences of slashing $52 billion from its budget next year.

In a letter to Secretary of Defense Chuck Hagel, the chairman and ranking member of the committee said that a compromise on deficit reduction between the White House and members of Congress remains elusive, making it increasingly likely that the drastic budget-slashing process known as sequestration will remain in place.

Despite dire warnings from defense leaders about the impact of the cuts on force readiness, Sens. Carl Levin (D-Mich.) and James M. Inhofe (R-Okla.) wrote that many members of Congress have come to see sequestration as “an effective way to cut government spending.” They added: “As a result, there is an increasing risk that [the Pentagon] and other federal agencies may face sequestration again in 2014.”

The Obama administration’s $526.6 billion proposed 2014 defense budget was drawn up under the assumption that sequestration would be nixed by next fall, when the new fiscal year begins. If it remains in place, the senators estimate that the Pentagon would have to find $52 billion in cuts.

Levin and Inhofe told Hagel in the letter that detailing the impact of the shortfall could serve as “a concrete demonstration of the painful choices the department would have to make,” adding that it might be its “last, best hope of avoiding sequestration altogether.”

Inhofe said the Pentagon last year, under Secretary of Defense Leon E. Panetta, operated under the assumption that sequestration was such a misguided approach that Congress and the White House would surely compromise to avert it.

“Our military was told last year not to worry about sequestration, that it would not happen,” Inhofe said. “But the failed promise has led to an enormous amount of uncertainty that has prevented our military leaders from properly planning to ensure the capabilities and readiness of our force.”

Claude H. Chafin, a spokesman for the House Armed Services Committee, said its chairman welcomed the effort to “better highlight the strategic cost” of sequestration.

Lt. Col. Elizabeth Robbins, a Pentagon spokeswoman, said Hagel would respond to the senators’ letter. “The readiness of our force is rapidly eroding due to mandatory sequestration cuts,” she said in an e-mail. “We are deeply concerned about sequestration continuing into the next fiscal year.”

Since sequestration took on an air of inevitability last spring, military leaders have made dire predictions about the impact the cuts will have on a force grappling with the wear and tear of two lengthy wars.

Testifying before the Senate committee recently, Secretary of the Army John McHugh said that failing to do away with sequestration before the end of next fiscal year would be “irresponsible” and “devastating” and call into question the military’s ability to “provide sufficiently trained and ready forces to protect our national interests.”