Centre Alliance senator Rex Patrick says his small but crucial party will be ramping up pressure on the Morrison government to boost Newstart.
Two Senate crossbenchers are hatching a plan to increase welfare for job-seekers, but the coalition's lower house majority threatens to foil their efforts.
Social services groups have long called for a boost to Newstart - the payment to people looking for work - which hasn't increased in real terms for more than two decades.
It is currently $555.70 a fortnight for a single person without children.
Centre Alliance senator Rex Patrick says he and upper house colleague Stirling Griff raised the issue of increasing Newstart when negotiating with the government on its income tax cut package.
"It wasn't an area they were willing to go down," he told Sky News on Thursday.
The senators instead backed the tax cuts on Thursday after negotiating with the government on measures to keep gas prices at bay, to ensure the new tax relief won't be chewed up by rising power costs.
But Senator Patrick said they're looking at other ways to increase Newstart.
"Centre Alliance have a bit of a plan in relation to that, moving forward," he said.
The plan is likely to involve Tasmanian senator Jacqui Lambie, he said.
"People like Jacqui Lambie and Centre Alliance can work together. We both have a similar view about Newstart.
"We'll be looking at ways we can put pressure on the government moving forward to address that area, because it is problematic."
Centre Alliance's two Senate votes are crucial as the government needs the support of Labor or at least four crossbenchers in the upper house to get any legislation through.
Labor had vowed to review the Newstart payment if it won the May 18 election, with the intention of lifting it.
Opposition frontbencher Tanya Plibersek said she still believes an inquiry should be held.
"It's really something we need to look at," she told Sky News on Thursday.
Shadow treasurer Jim Chalmers last month said Labor would not pursue its own review from opposition.
"If people want to see a boost to Newstart, then they have to convince the government," he told the National Press Club.
Even if Centre Alliance is able to rally momentum for a Newstart rise in the Senate, the push is likely to face an uphill battle without coalition support.
Labor and crossbenchers could rally together in the lower house, but their 74 combined seats will still be trumped by the government's 77-seat majority.
Independent Tasmanian MP Andrew Wilkie, who is in favour of a Newstart rise, said it's often left to the crossbench to address such issues.
"There are so many problems that can be addressed in part by lifting Newstart," he told Sky News.
"It helps solve the housing crisis, it helps people have the money to see their GP to stay out of hospital, so it takes the pressure off the hospital."