Canadian Prime Minister Justin Trudeau’s future looks uncertain following the sudden resignation of his most senior cabinet member, a once 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 disagreements she had with him on spending and “the best path forward for Canada”.

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

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

He faces a few options on how to move forward.