The Conservative government is considering splitting up its contentious, 420-page budget bill into several pieces of legislation under pressure from the opposition, New Democrats said Tuesday.

NDP House Leader Nathan Cullen said Government House Leader Peter Van Loan is contemplating the NDP's proposal to break up the massive omnibus bill into five separate pieces.

Cullen said he expected to hear from Van Loan late Tuesday or early Wednesday.

Opposition parties and environmental groups have been attacking the Conservatives' decision to limit debate on the budget bill, which includes amendments to about 60 laws, including environmental regulations, fisheries management and immigration law.

Critics have accused the Tories of trying to sneak in major reforms by lumping them all together in one large bill. Especially contentious are the proposed changes to environmental assessments for major projects, aimed at speeding up approvals for natural resource developments across Canada.

With only about a week set aside to debate the budget bill, the government has been under pressure to split it up so that the proposed reforms can be better scrutinized.

The Conservatives were on the defensive Monday, insisting they're allowing more debate than the Liberals did on any of their budget bills.

Finance Minister Jim Flaherty has said the bill will not be altered, while Van Loan accused critics of trying to stall economic stimuli and job creation.

But on Tuesday, a spokesperson for Van Loan would only say the minister is "constantly having discussions with opposition House leaders on all matters." He did not elaborate, nor did he rule out tweaks to the omnibus bill.

"Sending a 400-page bill that covered 60 different statutes to a sub-committee of finance just didn't make any sense," NDP Leader Thomas Mulcair told reporters Tuesday.

"The number one thing that we're elected to do is to hold the government to account and make that analysis on behalf of all Canadians and we plan to do our jobs correctly."

If the government refuses to split the bill, Mulcair said the NDP may pursue other "legal" and parliamentary avenues.

"We have a lot of options and we'll exercise them," he said.

With files from The Canadian Press