Labor has backed a hike in the top income tax bracket, but other federal budget measures face a tougher path.

Labor has backed a temporary income tax levy on high-income earners through parliament, handing the Abbott government its first budget victory.

But the government is facing internal criticism over its plan to raise petrol taxes and slow down the growth in pension and welfare spending.

The temporary budget repair levy, which passed the Senate on Tuesday, increases the top income tax rate, which applies to any income earned over $180,000, from 45 per cent to 47 per cent from July 1.

It aims to collect an extra $3.2 billion over three years.

Critics of the levy, including Liberal senators Ian Macdonald and Cory Bernardi, did not have to show their hands because the laws passed the upper house on the voices on Tuesday.

Earlier, the Liberal-National party room approved laws to reintroduce regular indexation of fuel excise.

From August 1, fuel excise will rise twice a year in line with inflation, after being locked at 38.1 cents since the Howard coalition government froze automatic indexation in 2001.

In its first year, the measure means motorists will pay about 60 cents more for a tank of petrol.

Facing questions from coalition MPs, Treasurer Joe Hockey agreed to model the tax hike’s impact on people in rural and regional areas.

Another MP told the party meeting the government needed to do more to convince voters of its benefits.

Taking on the issue in parliament, Prime Minister Tony Abbott said every cent raised by the tax would go to roads.

“This is a budget which delivers in spades for country Australia,” he said.

Labor seized on a comment by Finance Minister Mathias Cormann who told parliament reducing the “spending growth trajectory” would impact on individuals, families, pensioners, organisations, states and territories that receive payments from the federal government.

Shadow treasurer Chris Bowen said the government appeared to be “pathologically incapable” of understanding people’s opposition to the budget.

Mr Abbott insisted pensions were safe under his government.

The budget debate came as Labor leads the coalition by an average 55.6 to 44.4 per cent in two-party terms over three polls taken in the past week.

The government aims to put pressure on Labor next week with the reintroduction of the carbon tax repeal bills, which Mr Hockey told parliament would save state governments almost $700 million a year.