Former parliamentary speaker Peter Slipper has lashed out at Coalition MPs, accusing them of abandoning their free market principles by opposing Labor's wheat deregulation bill.

The Opposition decided to vote against deregulation, but WA Nationals MP Tony Crook crossed the floor and backed Labor, while Liberal MPs Denis Jensen and Mal Washer abstained.

The bill abolishes Wheat Exports Australia (WEA) and the 22-cents-a-tonne charge it imposes on producers.

The legislation has split the Coalition, with east coast MPs against it and some West Australian MPs wanting to back it.

Mr Slipper, now an independent MP, voted with the Government, which won the vote 70-67.

He says deputy Liberal leader Julie Bishop and other Opposition MPs are hypocrites because they favour wheat deregulation but are voting the other way to avoid a fight with the Nationals.

"I suspect many of them will vote with a heavy heart with the Opposition, because there are many people on this side of the house who support the Government's intentions," he said.

"This is all about preserving the flawed and fatal and terminal leadership of the Leader of the Opposition, the Member for Warringah."

"I suppose you have to admire the Deputy Leader of the Opposition because she's supporting her leader - after all, she's supported how many leaders?

"How many leaders has she been deputy to?

"I find it abhorrent that the deputy Leader of the Opposition is prepared to say it's important to defeat the Government's legislation, but not on any manner of principle."

Earlier, Mr Jensen, a WA Liberal MP, said he would not oppose the Government's bill.

"Regulation is not a natural position," he said.

"Note that blue blood pumps through my heart.

"Time to tell weak-wristed, water-cooler dictators, 'hands off mate!'.

"It's their wheat and they should be able to sell it on their terms."

Deal to pass

Earlier Wednesday, the Government agreed to a deal with the Greens to get its wheat deregulation bill through Parliament.

Greens senator Rachel Siewert said her party would back the legislation in both houses after Labor agreed to support amendments in the Senate.

She said they would ensure a port access code of conduct was legislated and an oversight body was created.

Former Liberal MP Wilson Tuckey congratulated the Greens for supporting the bill.

But he said he was disappointed about the lack of support from his former WA colleagues, including Ms Bishop.

"As I have made very plain, I am extremely disappointed that there is not a total vote of WA Liberal members for this particular measure," he said.

The WA Farmers Federation has welcomed the deal.

Federation president Dale Park said he was not concerned which party backed the bill as long as it passed.

"We've said right from the start that we don't see any need for WEA, so it doesn't really matter how we get it, as long as we get what we wanted," he said.