Twitter has recently offered an unsettling window into the federal Conservatives’ flirtation with right-wing populism.

Last Wednesday, Senator Denise Batters appeared to suggest on the social-media platform that Liberal MP Omar Alghabra’s ability to comment on Canada’s dispute with Saudi Arabia was impacted by that country being his birthplace. (She subsequently apologized.)

On Friday, Conservative MP Shannon Stubbs displayed a misunderstanding of the justice system by attacking the appointment of Omar Khadr’s former lawyer as a judge, on the basis that he defended “a confessed murderer and terrorist.” (She subsequently doubled down.)

Story continues below advertisement

Then, on Sunday, came a six-part Twitter thread from Maxime Bernier. The runner-up in last year’s Conservative leadership vote warned that treating diversity as a strength risks subjecting Canada to “distrust, social conflict, and potentially violence,” as it is weakened by people who “reject basic Western values” and “want to live apart in their ghetto.”

There is no indication that Andrew Scheer sanctioned any of these outbursts. But they indicated what is bubbling up under his leadership – and why, if he wants to preserve the sort of big-tent party that Stephen Harper spent much of his time as leader trying to build, he should start asserting some control.

Mr. Scheer cannot reasonably be expected, as a rookie opposition leader, to impose the sort of caucus discipline that Mr. Harper did – especially with Mr. Bernier, who has fashioned himself a dissident playing to elements of his party’s base. Nor would such central control be desirable: It’s broadly positive for democratic representatives to be able to voice their views without fear of reprisal.

But through his public comments and messaging, and his stewardship of the Tories’ policy agenda, Mr. Scheer should be capable of taking the lead in setting and upholding his party’s identity and establishing some limits.

So far, he has fallen short – especially, of late, by allowing other MPs to take the lead with increasingly hyperbolic language overstating the challenges posed by asylum seekers.

The result is a party that seems to be shifting from a pragmatic conservatism that at its best appealed to large swaths of the electorate, toward something that at its worst could veer into outright xenophobia and reckless anti-institutionalism.

Canadians deserve a more responsible alternative to the Liberals than that. If Mr. Scheer agrees, it’s time for him to say so.