The government is seeking a deal with the Greens which would extend an inquiry into the controversial changes in exchange for the minor party's support for an unrelated overhaul of negative gearing and the capital gains tax discount.
Labor hopes to slash the $56 billion cost of the NDIS by moving hundreds of thousands of participants onto other state-run disability supports that are yet to be developed.
A snap parliamentary inquiry into the proposal was scheduled to hand down its report on Tuesday, but had delayed its deadline until Friday.
Two sources close to the committee have told AAP the report will not be published until Tuesday.
The reason for the delay was unclear, but it adds to questions about the future of the reforms, which state governments, the federal opposition and the Greens have criticised.
Disability groups told the probe vulnerable Australians could die under the government's proposal and NDIS providers would find it harder to do business.
Greens senator Jordon Steele-John expressed frustration at the report's delay, accusing the government of deliberately withholding it.
"The government demanded that disabled people, their families and advocates rush to prepare submissions and evidence for the inquiry, yet it is now dragging its feet when it comes to publishing the findings," he said in a statement to AAP.
"Disabled people deserve certainty, transparency and respect."
The coalition broadly supports reducing the cost of the NDIS but has concerns about sweeping ministerial powers, cuts to participants' social and community participation funding and what it considers a lack of focus on fraud.
It will seek to amend the bill before it goes to a final vote in parliament.
The Greens want the legislation withdrawn, arguing it will deprive disabled Australians of critical supports.
The minor party has issued a list of 11 changes it would like made, including ensuring no participant is removed from the NDIS until the state-run foundational supports are fully implemented, evaluated and proven effective.
It is calling for greater accountability for disability providers, the scrapping of blanket funding caps and additional safeguards to ensure people are not required to undergo unwanted medical interventions to access the scheme.
Health Minister Mark Butler defended the disability overhaul on Friday in the face of fierce criticism from the states, who say they are not ready to provide the support required.
'"We're working constructively with states,'' he said.
"That doesn't mean sometimes that there's not a bit of friction in the relationship."Â
State and federal NDIS ministers were meeting on Friday to discuss the details of the reforms, Mr Butler said.
The health minister conceded there would be "a bit of politics" involved in getting the changes through parliament but insisted the majority of MPs and Senators agreed the scheme had gone "off track".
