Canadian Prime Minister Justin Trudeau's future appears uncertain after the resignation of his most senior cabinet member, who was once a close ally.

Chrystia Freeland - the former deputy prime minister and finance minister - quit her posts on Monday with an open letter to Trudeau, in which she outlined her disagreements with him on spending and "the way forward best for Canada”.

Those disagreements, she said, were underscored by the threat of tariffs on Canadian goods from incoming US President Donald Trump - tariffs that economists say would ' could deal a devastating economic blow to Canada.

Questions are now being asked on Parliament Hill, including some members of his own Liberal Party, whether he can lead at this critical juncture.

He has a few options about how to move forward.

Trudeau has been the leader of the Liberal Party of Canada since 2013, and Prime Minister of Canada for just over nine years, since 2015.

Under the party's constitution, the leader can resign at any time. If it takes effect immediately, an interim leader will be appointed so that party members can convene and vote on a new permanent leader.

Trudeau could also choose to stay in office until that new leader is chosen.

As soon as a new leader is appointed, Trudeau would have to relinquish his prime ministerial powers and hand them over to his successor.

Trudeau is not indicating that he will voluntarily retire anytime soon.

In an emergency meeting with his caucus after Freeland's departure, Trudeau told fellow Liberal members of parliament (MPs) - including some who had directly called for his resignation - that he would time for reflection, according to several reports.

And in a holiday address to the Liberal Party faithful on Tuesday, he admitted there were "big challenges" in politics but said: "Difficult times are not a time to stop. It's time to be ambitious, smart."

Trudeau has been under pressure since the summer, due to his plummeting approval ratings and a string of special election losses of once-safe Liberal seats that spell big trouble for his party.

In October, he faced a small caucus rebellion, with 24 MPs signing a letter asking him to leave.

Opinion polls indicate that if a federal election were held in Canada today, the official opposition Conservative Party would win decisively.

Trudeau has continued despite these problems and has repeatedly promised to run as Liberal leader in the next election.

Only 13 out of 153 Liberal MPs have so far openly called away - almost half of them are not seeking re-election themselves, according to a finding by CBC News.

However, under the party's constitution, members can only formally vote for the leader after losing an election.

Riding high in the polls with a double-digit lead, the Tories have tried for months to trigger an election by launching a series of no-confidence votes in the House of Commons.

If a government loses a motion of confidence or a vote in the House, it is expected to resign or ask to dissolve parliament, prompting a federal election.

The government needs the support of a majority of the 338 members of parliament in a vote of no confidence. The Liberals are 17 seats shy of that.

Conservative efforts failed after the NDP or the Bloc Québécois supported the Liberals as a result of support advancing their own political priorities.

With parliament adjourning for the holidays on Tuesday, Trudeau won't face the threat of another confidence motion until at least the end of January.

On Monday, NDP leader Jagmeet Singh for the first time called on Trudeau to resign, making the Liberals' grip on power look increasingly shaky.

The leader of the House of the NDP told the broadcaster the CBC that their members would vote for a motion of no confidence if the prime minister was still the leader in the New Year.

One way Trudeau could avoid the vote is by prodding parliament - essentially a suspension that would stop all business, including debates and votes, without to dissolve parliament.

Although it is a normal part of parliamentary procedure, it is sometimes used by governments to buy time in a political crisis.

Parliament was most recently impeached by Trudeau in August 2020, when his government was facing an ethics scandal over its handling of a contract with a charity.

It was also used to avoid a vote of no confidence by Trudeau's predecessor, Conservative Prime Minister Stephen Harper, who brought parliament to a standstill in December 2008 when federal opposition parties were trying to form a coalition government. creation

Parliament resumed in January 2009. By then the coalition had collapsed, allowing Harper to remain in power.

Whatever Trudeau decides to do, an election in the coming months is inevitable.

Canada must hold its next election on or before October, and in the end, voters may decide its future.