Opposition frontbencher Simon Birmingham said a shift in the government's position on the stage-three tax cuts - scheduled to be introduced in 2024-25 - would undermine Labor pledges to maintain the changes.
"Any erosion of that would be a clear breach of that position by (prime minister) Anthony Albanese," he told ABC radio.
But Skills Minister Brendan O'Connor said the government's position hadn't altered, despite the tax cuts being reportedly up for debate.
"Of course, we are looking at the impacts on the budget," he told Nine's Today program.
Mr O'Connor refused to say whether the tax cuts were discussed at Wednesday's cabinet meeting.
"We are in a very difficult situation ... where inflation is very high, people are struggling because of the interest rate hikes, which is impacting on their mortgage payments," he said.
"We understand that people are doing it really tough and that will inform our decisions in relation to the budget.
"But as for stage three, we have not altered our position."
There has been speculation the government is considering changes to the legislated stage-three tax cuts, which will provide the most benefit to high-income earners.
Ministers have consistently stood by the plan to reduce the marginal tax rate to 30 per cent for people earning between $45,000 and $200,000 from July 2024.
Finance Minister Katy Gallagher on Wednesday reiterated the government hadn't shifted its policy but did not deny changes were being discussed.
When asked about the current economic headwinds, Senator Birmingham said a better-than-forecast budget bottom line and a strong economy had put the nation in good stead.
"Conditions haven't significantly changed since the election," he said.
But Labor Party president and former federal treasurer Wayne Swan disagreed, saying the government would be naive to not consider international factors ahead of the upcoming budget.
He said the government had not broken an election promise to keep the state-three cuts as no decision had been made.
"I don't know whether they are going to change their view," he told Today.
"But any government that sat down in this environment and said they weren't going to review all of the policy settings in light of what has gone on, would be sticking its head in the sand."
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