Labor's ambitious tax agenda could face a major stumbling block if the party wins the election with a key crossbench party opposed to the signature reforms.
Centre Alliance is aiming to boost its representation to at least three senators at the election, with neither of its current upper house members up for re-election.
At the top of the South Australian party's ticket, Skye Kakoschke-Moore is gunning for a return to Canberra after losing her seat for having dual citizenship in November 2017.
She confirmed the former Nick Xenophon Team would oppose Labor's plan to scrap cash rebates to some Australian shareholders at tax time.
"This is one of those issues that's literally become a barbecue-stopper," Ms Kakoschke-Moore told Sky News on Friday.
She said the franking credits policy was unfair because people had made retirement plans around the system.
"It is one of those issues that's causing a massive amount of concern in the community."
The opposition is eyeing billions in revenue from the plan, along with an overhaul of negative gearing and capital gains tax.
Centre Alliance will only support a modified version of those proposals, arguing the policies are too blunt.
As for the coalition's income tax cuts, the minor party supports the three-stage plan conditional on an assessment of the economy when the final stage takes effect in 2024/25.
Tax has emerged as a key policy battleground for the major parties.
The government's plan would see everyone earning between $45,000 and $200,000 on the same 30 per cent marginal tax rate from July 1, 2024.
Labor argues the tax cuts benefit the rich and will need $40 billion in cuts to services to be delivered alongside budget surpluses, a claim the government strongly denies.
Conversely, the coalition says Labor is planning $387 billion in new taxes to fund its agenda.
Ms Kakoschke-Moore was replaced in the Senate by Tim Storer, who quit the party to sit as an independent.
Senator Storer announced on Thursday he would not recontest his seat at the May 18 election.
