Another landmark policy loss is looming for the Abbott government, as Senate crossbenchers firm in their resolve to sink a $22 billion cut to pensions.

Just days after the Coalition's defeat on its higher education reforms, Palmer United Party's Zhenya "Dio" Wang and independent senator Glenn Lazarus have signalled their opposition to Scott Morrison's fresh bid to change pension indexation - where a lowering of the indexation rate would be accompanied by regular reviews of pension adequacy.

Senator Wang and Senator Lazarus' opposition follows that of independent senator Jacqui Lambie and strong reservations expressed by South Australian senator Nick Xenophon.

While fellow crossbenchers John Madigan and Ricky Muir are yet to state their positions and senators Bob Day and David Leyonhjelm have been more receptive to the Social Services Minister's proposal, even if all four agreed this would not provide the six votes the Coalition needs to pass legislation.

The government announced in the 2014-15 budget that it would lower the rate of pension indexation from September 2017, linking it with inflation instead of wages growth.

This was met by staunch opposition from Labor, the Greens and the crossbench. But there have since been hopes that Mr Morrison, who took over the portfolio in December, would be able to pass the outstanding measure before the next budget is handed down in May.

The change in pension indexation has been projected to save more than $22 billion over 10 years by the Parliamentary Budget Office.

Mr Morrison, who describes himself as a "fixer", recently proposed that the indexation change be accompanied by an independent review of pension "adequacy" every three years.

But Senator Lazarus' concerns have not been assuaged by the safety net idea, arguing it would only create more stress for pensioners.

"The concept of a three-yearly review [means] pensioners will no longer be able to plan for the long term and will be subjected to pension changes every three years," he said.

"Pensioners will be at the mercy of a review every three years. This is no way to live."

A spokeswoman for Senator Wang said he was not yet convinced to support the bill "because in the end it will still be a cut to the pension".

A spokeswoman for Mr Morrison said the minister remained in "open discussions with crossbenchers".

"The measure remains a proposal by the government and the government is in no rush to have legislation proposed as it wouldn't take effect until 2017."

It is understood discussions with the crossbench are only in the very early stages, and there is no bill reflecting the new proposal before the parliament as yet.

Mr Morrison has been stressing that the pension needs to be "sustainable over the long period of time". It is currently projected to increase from 2.9 per cent of GDP to 3.6 per cent by 2054-55 if no changes are made.

But the renewed crossbench opposition will add fuel to a push from within the Coalition's own ranks to drop plans to make changes to the pension.

Queensland MP Andrew Laming has recently said there are "a couple of large missiles" aimed at the policy.

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