OTTAWA — Opposition parties banded together to save the long-gun registry, now they're trying to rescue the mandatory long-form census.

The Liberals submitted details to the House of Commons on Thursday of a private member's bill that would specifically insert the mandatory long-form census into the Statistics Act.

The bill could see first reading in the Commons by Oct. 1, and the opposition hope they can hurry it through second reading and on to committee hearings.

The Bloc Quebecois and the NDP said Thursday they would support a bill to resurrect the mandatory long form.

Currently, the Act only refers to the requirement to hold a census of the population -- the short census -- every five years.

The Liberal bill would also remove the threat of jail time for those who refuse to fill out the long form, but keep the maximum $500 fine.

"It's almost a sacred trust that we have with civil society that we will get them the information they need with which to plan, and whether that's the Bank of Canada, or the public health officials, or the Canadian Federation of Independent Business, people are counting on this information and it must be comparable data with previous censuses," said Liberal Carolyn Bennett, the bill's sponsor.

"If, all of a sudden, the methodology changes, no matter how much tweaking they say they can do by trying to improve the voluntary census, there is no way you can have the quality of data."

The Conservative government eliminated the mandatory long-form census in June, citing concerns among some Canadians that the process was intrusive and the threat of jail time unreasonable. They replaced it with a voluntary national survey, that would be distributed to more households.

The move set off a wide backlash from a variety of opponents, including religious groups, major charities, the Federation of Francophone and Acadian Communities, statisticians and academics. Several provinces and large municipalities also balked, saying the loss of data would skew policy-making.

Former chief statistician Munir Sheikh resigned in the wake of the decision, unable to support the government's contention the survey would adequately substitute for the long-form census.

Both Bloc Leader Gilles Duceppe and NDP Leader Jack Layton were unequivocal Thursday in their support of a bill to revive the long-form.

"Legislation, although it would take time to put in place, is something that absolutely we would support," said Layton, who earlier called unsuccessfully for an emergency debate on the subject.

Industry Minister Tony Clement stood by the government's decision during question period Thursday.

"We are working in a fair and reasonable way to have a balance between the need for data and the idea that we should not coerce or force our citizens who may conscientiously object to giving very private information to government officials," Clement said.

Bennett argues there is enough time to act before the next census, scheduled to begin in May 2011.

The Liberals also believe there will be no obstacles to the bill as it makes its way through the parliamentary process.

Bills that involve the expenditure of public money must be introduced by the government, but Bennett notes that reinstating the long-form census would ultimately save money. She said Ottawa is spending at least an extra $30 million on the short census and voluntary survey to get it to more households and encourage responses.