After more than six weeks of sometimes testy talks, House and Senate negotiators have agreed on a compromise plan to fix a veterans health programme hit by long patient waiting times and falsified records covering up delays.

The chairmen of the House and Senate veterans affairs committees have scheduled a news conference for Monday afternoon, to unveil a plan expected to authorise billions in emergency spending to lease 27 new clinics, hire more doctors and nurses and make it easier for veterans who cannot get prompt appointments with VA doctors to obtain outside care.

The agreement reached on Sunday by Representative Jeff Miller, a Florida Republican, and Senator Bernie Sanders, an independent from Vermont, was a long time coming. The House and Senate approved bills on veterans healthcare in early June, and lawmakers from both parties said they expected a final bill by 4 July.

Instead, negotiators met once in public, then disappeared or held private meetings that produced few results. Talks reached a low point last Thursday, as Sanders and Miller had a public spat that appeared to leave the two sides far apart, with only days remaining until Congress goes on a five-week recess.

Sanders, who chairs the Senate veterans panel, and Miller, chairman of the House panel, repeatedly lashed out at each other. Sanders accused Miller of acting in bad faith, while Miller said Sanders had "moved the goalposts" in talks to fix veterans' healthcare. A partisan impasse loomed, even as both sides said they hoped to avoid what Miller called the "sort of bickering and name-calling for which Washington has become infamous”.

Three days later, after talks by telephone, Miller and Sanders were on the same page. Aides to the two men said on Sunday they had reached a tentative agreement. The deal requires a vote by a conference committee of House and Senate negotiators, and votes in the full House and Senate.

Miller and Sanders said in a joint statement that they "made significant progress" over the weekend toward agreement on legislation to reform the Veterans Affairs department, which has been rocked by reports of patients dying while awaiting VA treatment and mounting evidence that workers falsified or omitted appointment schedules to mask frequent, long delays. The resulting election-year firestorm forced VA secretary Eric Shinseki to resign in late May.

The plan set to be announced on Monday is intended to "make VA more accountable and to help the department recruit more doctors, nurses and other health care professionals”, Miller and Sanders said.

Louis Celli, legislative director for the American Legion, the nation's largest veterans group, said the deal would provide crucial help to veterans who have been waiting months or even years for VA healthcare.

"There is an emergency need to get veterans off the waiting lists. That's what this is all about," Celli said on Sunday.

Tom Tarantino, chief policy officer of the Iraq and Afghanistan Veterans of America, said the agreement was good news – although several months late.

"It's about time they're doing their jobs," he said of Sanders, Miller and other members of Congress. "You don't get a medal for doing your job."

Veterans waiting two months for medical appointments "don't care about all this back and forth" in Congress, Tarantino said. "That's what should be driving decisions."

An updated audit by the VA this month showed that about 10% of veterans seeking medical care at VA hospitals and clinics still have to wait at least 30 days for an appointment. About 46,000 veterans have had to wait at least three months for initial appointments, the report said, and an additional 7,000 veterans who asked for appointments over the past decade never got them.

Acting VA secretary Sloan Gibson has said the VA is making improvements, but said veterans in many communities still are waiting too long to receive needed care. The VA provides healthcare to nearly 9 million enrolled veterans.

The House and Senate are set to adjourn at the end of the week until early September, and lawmakers from both parties have said completing a bill on veterans' healthcare is a top priority.

The Senate is expected to vote this week to confirm former Procter & Gamble chief executive Robert McDonald as the new VA secretary, replacing Gibson.