Finance Minister Mathias Cormann is putting pressure on Labor to support the coalition’s tax plan, after again warning against any attempt to split the package,

Senator Cormann has been locked in negotiations with the Senate crossbench over the 10-year income tax relief plan.

One Nation was demanding action on power prices and water storage in return for its support, while the Centre Alliance wanted more help for pensioners.

But Senator Cormann, who is the coalition government’s leader in the Senate, now appears to be playing down negotiating special deals to get it passed, pressuring Labor to back its plan.

While Labor supports the first tranche of the tax package – geared toward low and middle-income earners – but not the government’s aim to flatten the tax structure in 2022 and 2024 under the second and third stages of its plan.

But the finance minister remains adamant the package won’t be split up.

“Any attempt by the Senate to split the package would be rejected by the government in the House of Representatives,” he wrote in an opinion piece in The Australian on Friday.

“So the way for Labor to help deliver income tax relief for low-income earners quickly is by voting for our entire plan both in the house and in the Senate in the first week of July.”

Not flattening the tax structure will see more Australians pushed into higher income tax brackets due to inflation, he added.

Without Labor’s support, the Morrison government needs support from four of six crossbenchers to legislate the cuts when parliament resumes in three weeks’ time.