Hero to zero.

That’s the transformation that takes place in politics, if you overstay your welcome. And it happens pretty fast, too.

That’s why they say a week is a long time in politics. Because it is.

One day you’re on the cover of Rolling Stone, being touted as the literal personification of wokefulness — and the next day you’re miserable and cooling your heels in India, because your plane broke down and no one wants to shake your hand anymore. Boom. From hero to zero, just like that.

Politics is weird in that way, and unforgiving. Brian Mulroney won two big majorities, and ended his tenure with the support of 12% of Canadians. Paul Martin was supposed to be a juggernaut, a Toronto Star columnist decreed, and then went from juggernaut to after-thought.

Stephen Harper was supposed to be Mr. Economics, started fretting about niqabs and “barbaric practices,” and thereby got clobbered by no less than hopey-wokey Justin Trudeau. (That barbaric practices nonsense, by the by, was cooked up by Pierre Poilievre’s brain trust. Hero to zero can happen to anyone, and does.)

And so on and so on. One minute everyone wants a selfie with you, applauding when you hijack a plane. And, the next minute, they’re looking at the tops of their shoes when you enter the room.

Trudeau has experienced metamorphosis in reverse. He started off as a beautiful and delicate butterfly, flitting from one social justice flower to the next. And now he’s turned into a caterpillar, chewing away at leaves and detritus in the dark. He is in profound danger of being stepped on by voters.

Fifteen points! Young people! Liberal strongholds! Those are the things he’s lost, in his devolution into something less than he was. Without them, he’s hooped.

How did it happen? Lots of reasons. Serial scandals, over-promise and underdeliver, circumstances and events. But, mainly, it’s because he’s become the party guest who won’t leave.

The hosts are sweeping the floors and putting away the silverware, but Justin still sits over in a corner, loudly recalling past glories and the time Melania Trump gave him a look you could pour on a stack of waffles. He won’t leave.

He doesn’t listen to many, ever, but he was indeed advised by a few smart folks to start inching towards the exits. One majority and two minorities is plenty, he’s been told, something about which to be proud. That’s a decade. As good as it gets.

But he demurred. He declined. He deferred. And, now, it feels like it is too late to install a fresh new Liberal face, and rescue the brand of the Liberal Party of Canada. Smart Liberals know that another victory is impossible. They just want to save the furniture, now.

Trudeau, the caterpillar who thinks he’s still a butterfly, doesn’t get it — or he doesn’t care.

This writer’s working theory is that — like many men — his father’s shadow looms large over Justin’s path through life. He wants to equal, or surpass, his father’s record. (It happens. Ask George W. Bush about it.)

Whatever the reason, he is just about out of time. If he doesn’t leave — and for the love of God, Justin, please leave — he’s done like dinner. He’s got to Christmas to rescue the party. Maybe.

Hero to zero. It’s a political cliché, sure.

But it’s also Justin Trudeau.