Liberals choose their leader today, after campaign defined by chaos of Trump administration

Tonight the Liberal Party will announce its next leader and the person who will soon become prime minister — a job they'll inherit amid economic turbulence and a deeply wounded relationship with the country's once closest ally.

The party's choice — who would become prime minister only after being sworn in by the Governor General — not only represents a new chapter for the Liberals but could also mean the imminent start of a federal election.

CBC News will bring special coverage of the historic event beginning at 4 p.m. ET.

Those vying for the job are former central banker Mark Carney, former finance minister and current MP Chrystia Freeland, former House leader and current MP Karina Gould and Montreal business leader and former MP Frank Baylis.

• On today's episode, Cross Country Checkup is asking: Who should be the next Liberal leader? Leave your comment here and we may read it or call you back for our show.

The relatively short leadership race was triggered when Prime Minister Justin Trudeau announced in early January his intention to step down following mounting caucus revolt and the resignation of Freeland from cabinet.

At the time, the party was in a deep polling slump, trailing Pierre Poilievre's Conservatives by more than 20 points. Recent polling suggests the Liberals are bouncing back. Whoever wins will be under pressure to sustain that momentum.

The campaign has seen candidates move away from Trudeau-era policies like the carbon tax and changes to the capital gains tax, while putting their own spin on how to deal with the housing crisis and make life more affordable for Canadians.

But domestic issues have been overshadowed by the existential threat that U.S. President Donald Trump poses. The race largely became a question of who would be best to handle the fallout of his tariffs and threats. 

After nearly two months of campaigning and two debates, that decision is now in the hands of thousands of registered Liberals. Eligible voters have been able to cast their ballots for over a week and have until 3 p.m. ET to get their votes in.

How will the party tally up the votes? 

While much has been said about how Carney — who has amassed the most caucus support, pulled in the most money and is the main target of the Conservatives — is the front-runner, the four campaigns' get-out-the vote efforts will play a role tonight.

The Liberals are using a ranked ballot and a point system to determine the winner. Every riding (there are now 343 after boundary changes) is worth 100 points, meaning 34,300 points are up for grabs. The candidates are assigned points depending on what percentage of the vote they get in each riding. 

The leader must win a majority of the total points. The magic number is 17,151.

Party members can choose up to four people for leader, ranking their preferences from first to last.

If no candidate reaches the 17,151 threshold in the first round, the person with the fewest points is eliminated and the ballots get counted again. If that's the case, points will be reassigned based on members' second choices.

That process will continue until a winner emerges.

One of the first questions for the victor will be whether they plan to immediately trigger an election or wait until Parliament returns March 24.  

Sunday's event is being be held in Ottawa and Trudeau and former prime minister Jean Chrétien are slated to speak to the crowd.

Just a few days ago, Trudeau said he expects the transition to his successor to happen "in the coming days or week." 

The Liberal Party limited voting to Canadians and permanent residents, citing foreign interference concerns. 

To vote in this race, registered Liberals had to get an electronic voter ID, then verify that ID online. They then had to confirm their status as an eligible voter. After that they had to confirm their identity using the Canada Post Identity+ app or in person at a participating post office.

That system has been plagued by irritants, with members complaining they've been unable to get the process to work, particularly when it comes to the mobile app and in-person option to verify their identity.

The party said the system for the Liberal leadership is "the most secure and accessible voting process in Canadian history."