A post by an Alberta Tory leadership contender on the weekend provoked a backlash on Twitter.

Jason Kenney, who is campaigning to lead the Progressive Conservative Party and then unite the right in Alberta, tweeted a photo of what appears to be a child dressed as an Israeli soldier on his knees with two other children holding toy guns to his head.

Kenney's tweet says, "Root cause."

The photo came from a Fox News story about a children's festival in Gaza that the news agency claims celebrated the killing of Israeli troops.

The tweet was liked more than 100 times, but it also spurred dozens of tweets condemning the former federal politician for engaging in what several called "dog whistle" politics.​

"Combating anti-Semitism has been a central issue for Jason Kenney during his 19 years in Parliament," a spokesman for Kenney's campaign said in an email to CBC News. 

"His social media posting was made in that context, underscoring that one of the root causes of violent anti-Semitism is the inculcation in children of this uniquely durable form of hatred."

Mount Royal political scientist Lori Williams said Kenney's tweet comes across as fear mongering.

"It's inexplicable, frankly," she said. "He seems not to have learned the lessons of national politics where you have to be very moderate on the right if you're going to generate broadly based support."

Williams says the tweet will remind people of his controversial directive while he was the federal immigration minister to forbid Muslim women from wearing niqabs while taking the citizenship oath.

Kenney responded to several of his critics on Twitter, saying that "exposing the inculcation of anti-Semitism in children" is necessary in order to combat it.

With files from Jennifer Lee