By Paul Vieira 

OTTAWA -- Canada's Liberal government on Monday began the task of ratifying the revised North American trade deal, a process that could take months and force Prime Minister Justin Trudeau into some deal making with rivals to ensure quick passage.

Canada is the last country remaining to yet ratify the revised trade deal, following the conclusion of talks between the Trump administration and the Democratic-controlled House of Representatives. Mexico did so in December and the U.S. Senate this month. President Trump is scheduled to sign the revised U.S.-Mexico-Canada trade pact, or USMCA, into law on Wednesday.

The trade pact marks an important political victory for Mr. Trump as he heads into a re-election campaign. He will cite USMCA as evidence that he is improving the lot of America's working class by revamping trade deals that he argued put the U.S. at a disadvantage.

The pact won't come into force until 90 days after the last country ratifies the deal. The timing of Canadian approval remains a wild card as the governing Liberals try to navigate a minority government, which gives the opposition parties -- which have criticized elements of the deal -- some leverage.

Any perceived foot dragging could fuel unease and unrest from the Trump administration and perhaps even Mexico, as both are eager to move on and put their focus elsewhere, trade watchers say.

"This won't be a rubber stamp," said Mark Warner, a trade lawyer who practices in Toronto and New York and has closely followed the USMCA talks. "It will get passed but there will be bumps."

A representative from the U.S. Embassy in Ottawa didn't respond to a request for comment. A spokesman for the Mexican Embassy in Ottawa said Mexico anticipates "a lively discussion"among Canadian lawmakers, "but we trust that in time Canada will ratify" the deal.

The government introduced a motion in Parliament that formally kicked off the ratification debate, with legislation to follow on Wednesday that would bring Canada's laws into compliance with USMCA.

Deputy Prime Minister Chrystia Freeland told reporters Monday the passage of USMCA marked a pivotal moment for the country, and she called on opposition lawmakers to put partisanship aside and "pass the legislation without undue delay."

Ms. Freeland, who led Canada's trade-negotiating team, declined to offer a time frame on when ratification would be complete. She said she is willing to listen closely to opposition lawmakers' concerns.

"The ball is in the opposition's court," she said. "Any uncertainty around our trading relationship with the U.S. that remains is now entirely the choice of Canadians. Are we ready to end the uncertainty and to move forward?"

The Conservative Party has said it would back ratification -- although with misgivings. A Tory official said the party wants to ensure the deal gets the proper due diligence.

"We are not going to play any games," said Randy Hoback, a Conservative lawmaker with responsibility for reviewing trade policy. "But we want to know the workaround game the government has in mind for sectors that have been adversely impacted," he said, citing the country's agricultural, forestry and aluminum producers.

Collectively, the opposition parties now have control of the legislative committees in a minority government. They could slow down ratification if they all insist on a lengthy list of witnesses to testify.

The Bloc Quebecois, with the third-most seats in the Legislature, have signaled its opposition to the trade pact, because of potential harm to Quebec's dairy farmers and the province's aluminum producers. "I'm sorry to rain on their parade," said Bloc leader Yves-François Blanchet.

The left-wing New Democratic Party, which tends to oppose free-trade agreements, said it wants a fulsome debate before deciding its vote on USMCA. "There's still some ongoing concerns about the changes that were made to help protect workers and the environment," party leader Jagmeet Singh told reporters last week.

Karl Bélanger, a political commentator and former senior NDP aide, said opposition parties are trying to extract a deal from the Liberals that would address their concerns without reopening USMCA. He expects ratification to take months.

The opposition "are trying to stake some territory with a win, to show Canadians they can be trusted on a particular issue," Mr. Bélanger said.

Another wild card is Canada's Senate. The upper chamber has rarely blocked government legislation. However, its members, who pride themselves on being independent, could opt for a thorough review of USMCA before lending its approval.

"Will the Senate use its veto power? No," said Lori Turnbull, a political-science professor at Dalhousie University in Halifax, Nova Scotia. "But will senators take their time in asking a lot of questions? Yes."

A spokeswoman for the Liberal government's representative in the Senate, Don Gold, wasn't immediately available for comment.

Write to Paul Vieira at paul.vieira@wsj.com

(END) Dow Jones Newswires

January 27, 2020 14:34 ET (19:34 GMT)