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As such, seven senators from both parties announced Monday afternoon they were introducing a bill to plug the hole in benefits funding.

"We fought to make the PACT Act law to expand the care and benefits millions of veterans earned when they served our country, and because of it, more veterans than ever are getting the care they deserve," Sen. Sherrod Brown, D-Ohio, said in a statement about introducing the bill. "We must ensure VA can continue to implement the PACT Act -- we can't deny the brave veterans who sacrificed to protect our country the benefits they earned, because VA doesn't have the resources."

In addition to Brown, the bill is sponsored by Sens. Patty Murray, D-Wash., and Susan Collins, R-Maine, the leaders of Senate Appropriations Committee; Jon Tester, D-Mont., and Jerry Moran, R-Kan., the leaders of the Senate Veterans Affairs Committee; and Kyrsten Sinema, I-Ariz., and John Boozman, R-Ark., the leaders of the Appropriations Committee's VA subcommittee.

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VA officials have attributed the benefits funding shortfall largely to an increase in disability claims driven by the PACT Act, which expanded VA eligibility and benefits to millions of veterans exposed to toxins during their military service. The shortfall is also being caused by higher than expected usage of GI Bill benefits, VA officials have said.

That explanation has not sat well with some lawmakers, who maintain the VA should have anticipated the PACT Act-related increases.

"I am gravely concerned that the administration, both at VA and [the White House Office of Management and Budget] specifically, misled Congress for months about the state of affairs at VA and the level of resources that are actually needed to care for veterans and their survivors," Moran said at an Appropriations Committee meeting last week.

Still, he added, Congress has no choice but to act to ensure "veterans and survivors do not suffer."

House Veterans Affairs Committee Chairman Mike Bost, R-Ill., similarly accused the VA of "fiscal mismanagement" in a letter to McDonough about the shortfall earlier this month.

Bost's letter also demanded McDonough answer a slew of questions about the shortfall by this past Friday or else face "compulsory processes," as in a subpoena, to get information.

McDonough sent Bost a response by his Friday deadline in which he defended the department's previous budget estimates and reiterated its stance that the shortfall is a sign of the department's better-than-expected implementation of the PACT Act. The response also pledged to provide a briefing to committee staff on some additional details.

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"As I testified to your committee in the spring, we thought the aggressive outreach we were conducting could result in our needing additional funding," McDonough wrote, according to a copy of the letter obtained by Military.com. "I pledged then that, if we did end up needing additional funding, we would come forward. Accordingly, we look forward to working with you closely to address these needs in a way that ensures no veterans will be adversely impacted and that we can continue to deliver care and benefits to veterans at record rates."

While McDonough responded by Bost's deadline, a committee spokesperson told Military.com the panel is still reviewing the answers and so the prospect of a subpoena is not off the table yet.

Asked about the ongoing subpoena threat, VA spokesperson Terrence Hayes told Military.com on Tuesday that the department has "responded directly to Chairman Bost's letter, briefed his staff and will continue to exercise transparency in answering his questions."

While senators have taken an initial step to prevent a disruption in benefits, time is running short in the legislative calendar to act before the VA's Sept. 20 deadline. Senators are scheduled to leave town at the end of the week until Sept. 9, and the House has already left for its summer recess that goes until the same date. That leaves just two working weeks for Congress to approve a fix.

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Another open question is how lawmakers will address the $12 billion shortfall in VA medical funding for fiscal 2025. Congress has yet to approve government funding for fiscal 2025, meaning lawmakers could still allocate more funding for VA medical accounts as part of the regular annual VA spending bill. But they also would have to reach a bipartisan agreement to ignore previously approved budget caps.

Asked at a news conference last week whether the VA has a workaround if Congress does not address the shortfalls, McDonough said that "the main thing we're focused on is getting this done."

"Obviously, it would be prudent for us to plan for that, but right now we're really focused on getting, in the first instance, this very straightforward fix for [the Veterans Benefits Administration] by the middle of September," he said. "We'll make sure that if, as we need contingency plans, we're talking about those so that we're informing veterans as well."