Finance Minister Jim Flaherty put on his best poker face Wednesday as he insisted the Conservative government's next budget implementation bill wouldn't contain any unexpected surprises.

Flaherty's second budget bill, to be introduced Thursday, is believed to contain measures to reform MP and public sector pensions, as well as a host of tax changes. But that's it, the minister insisted.

"The budget was published in the spring, everybody's had months and months to read it," he said after question period.

"There are no surprises."

Last spring's controversial omnibus legislation, denounced by critics as a "Trojan horse" bill, amended dozens of laws and included provisions not mentioned at all in the budget, like an end to oversight for the Canadian Security Intelligence Agency.

Critics fear the next bill will be no different.

"Last spring, Conservatives presented a bill that not only killed more jobs than it created, it weakened environmental protection, gutted the Fisheries Act and further cut EI to Canadians," NDP MP Nathan Cullen said during question period.

"Across the country people were clear, this is not how Parliament should work."

Opposition introduced hundreds of amendments

The Conservatives defended the use of omnibus legislation in the spring as a legitimate tool to ensure speedy passage of economic measures and have argued that bill received extensive debate.

That wasn't enough for the opposition, which introduced hundreds of amendments to the bill as a form of protest, forcing a marathon 24-hour voting session in hopes of drawing awareness to the government's tactics.

The Tories accused them of stonewalling economic measures but NDP Leader Tom Mulcair said they were just doing their jobs — and will do so again if necessary.

Without the amendments, most Canadians wouldn't have known about the changes to EI, old Age Security or environmental legislation, Mulcair said.

"So you can be sure that we will be doing that again if indeed they surprise us by not having a budget bill that deals only with job creation," Mulcair said.

MP pensions to be included

The fact that changes to MP pensions will be included in the implementation bill will require a political balancing act for opposition parties who could be seen as protecting their own pocketbooks if they refuse to vote in favour.

"We're quite happy to see members paying more into their pension plan, quite happy to see changes that make the pension plan more fiscally sustainable and more responsible," said interim Liberal leader Bob Rae.

"How we vote on the whole legislation will obviously depend on the whole legislation."

The opposition had asked the Conservatives to hive off the provisions relating to MP pensions into a separate piece of legislation, but the government refused.

A committee of Conservative backbenchers is crafting the pension reforms, which are expected to include boosting MPs' contribution rate to 50 per cent from 14 per cent and raising the age of eligibility to 65 from 55.