Stop us if you've heard this one before: Liberal MPs are voicing concerns about Justin Trudeau's ability to lead the party in the next election, saying that he should step down for the good of the party. No, this isn't June. Or August. The difference this time is in the sheer numbers of them, and that they've apparently drafted a formal letter ahead of Wednesday's caucus meeting. Will this be the shove that finally begins the exit process for the Liberal's longtime leader? If not, just how bad would the polls have to get? Does the party even have a mechanism to remove Trudeau without his consent? And if not, what would the next few months look like in Ottawa, as a leader attempts to govern without the support of some of his own party? GUEST: Glen McGregor, Parliament Hill reporter