Prime Minister Tony Abbott has promised an immediate drop in power prices should the Senate scrap the carbon tax as expected on Thursday.

The government now appears to have the numbers to push its package of repeal bills through parliament with the backing of at least six crossbenchers.

Speaking ahead of a vote on Thursday, Mr Abbott declared: “Today should be the day when the carbon tax is finally scrapped”.

The carbon tax was a nine per cent impost on power bills, a $9 billion “handbrake” on the economy, and a $550 annual hit for households, he said.

“If the Senate votes today as it should, people’s next power bill will be less than it would otherwise be,” he told reporters in Perth.

“Getting rid of the carbon tax is good news for families, is good news for business, good news for jobs and good news for prices.”

Passage of the carbon repeal would follow an embarrassing misstep on Wednesday, when the government tried to force a vote on its carbon repeal only to be stymied by new crossbencher Ricky Muir.

The Australian Motoring Enthusiast Party senator split from his Palmer United Party allies, to unexpectedly side with Labor and the Greens.

The miscalculation could have put the vote off until next week.

But Senator Muir later patched up his differences with PUP and agreed to vote for the carbon repeal on Thursday.

Australian Greens senator Christine Milne was taking solace in the fact at least the Clean Energy Finance Corporation, the Climate Change Authority and the RET would be saved.

She challenged the Palmer United Party senators to support an amendment to move the fixed carbon price to a floating price.

“The rest of the world is moving fast on decarbonisation and we will be left behind,” Senator Milne said.

The government won the numbers to force an urgent vote before noon on Thursday, after Senator Muir crucially sided with his PUP allies.

It will pass with a PUP amendment, meaning it will have to go back to the lower house for the tick of approval next week.