Calgary Mayor Naheed Nenshi was on a Toronto radio show Friday morning to defend the federal government's decision to buy the Trans Mountain pipeline.

Nenshi told CBC Toronto's local morning show that Ottawa was left with no better options than to nationalize the Kinder Morgan pipeline because of political game-playing by British Columbia Premier John Horgan.

"I've called Premier Horgan the worst politician in Canada in decades. Harsh, but also true," Nenshi said.

"Premier Horgan has been playing a very dangerous game. He knows he can't win in court, so his whole plan was to drag this thing out so long that the investors, who have plenty of other places to put their money, will say it's not worth investing in Canada."

The federal government will buy the Trans Mountain pipeline and related infrastructure for $4.5 billion, and could spend billions more to build the controversial expansion. (CBC)

Nenshi told Toronto listeners that the $4.5 billion Ottawa is spending to buy Trans Mountain is less than former Prime Minister Stephen Harper spent on the bail out of the auto sector during the 2008 global financial crisis.

And unlike that situation, there is certainty that, once the pipeline is built, it will turn a profit, he added.

A former CEO of TransCanada Corporation says the federal pipeline purchase puts the project in a better position to deal with any further opposition.

Hal Kvisle says though there are significant risks of further delays and cost overruns, by starting construction in the Burnaby area, the government will be better able to judge the true opposition to the project.

"I think that's probably a good idea. Go right into the hotbed of opposition and start there," he said.

"And I think that, until construction actually commences, there's no way of knowing how much opposition's going to show up on the ground. And there's no way of knowing what sort of police or security presence is going to be required to deal with it."

Kvisle also says the federal purchase was the best possible deal it could make given the circumstances.