Expect a showdown Wednesday over the Department of Veterans Affairs health scandal on Capitol Hill.

A House committee will question the agency's acting inspector general about a report on dozens of patient deaths at the Phoenix Veterans Hospital.

Two of the doctors who first blew the whistle on the veterans' deaths in Phoenix say the inspector general botched the investigation and went too easy on the Department of Veterans Affairs (VA).

One says the IG engaged in a whitewash of what happened there, bowing to pressure from inside the agency, reports CBS News correspondent Wyatt Andrews.

The issue surrounds the investigation into whether more than 40 veterans at the Phoenix VA died while waiting to see the doctor. The IG's final report in August concluded that it "[could not] conclusively assert" that long wait times "caused the deaths of these veterans."

According to one whistleblower who spoke to CBS News, however, that crucial assertion was not in the original draft of the report. He told CBS News that the Inspector General added the line about how wait times did not cause the deaths at the last minute.

Our source, who works at VA headquarters and who spoke exclusively to CBS News, said officials inside the agency asked for a revision of the first draft. That's standard practice, but in this case the source said it amounted to pressure on Inspector General Richard Griffin to add a line to water down the report.

"The organization was worried that the report was going to damn the organization," the whistle-blower said. "And therefore it was important for them to introduce language that softened that blow."

The Office of the Inspector General issued a statement rejecting our whistleblower's claim saying: "There was no pressure from [the] VA to add this line."

"We did not find sufficient evidence (that any) delay resulted in death," added the statement.

But that conclusion, that no deaths were caused by delays, seemed to conflict with the rest of the report. For example: "28 instances of clinically significant delays" were found, including delays linked to six deaths. And findings indicated either "treatment" or "an appointment for this patient might have changed the outcome."

The inspector general's finding was also a surprise to some of the families who lost relatives.

Teddy Barnes said his father Thomas, Navy veteran, died while on a secret wait list, but no one from the Inspector General's office ever called his family.

"He was a good guy, you know," said Barnes. "It sounds like they're either trying to cover it up or sugar-coat it a little bit, because we didn't hear anything about this."

Now, newly released figures show that 293 veterans died -- not 40 -- while on those secret wait lists. That does not mean the veterans died from lack of care, but families are already asking if the Phoenix investigation should be reopened.