It was expected that the 2015 Alberta provincial election would end like the twelve that came before it: with the Alberta Progressive Conservatives being elected to another majority government. Instead, Rachel Notley's New Democrats pulled off what previously would have been an unthinkable upset — ending 44 years of PC government in the province.

Polls now suggest the NDP will struggle to establish a dynasty of its own this year. So how did the NDP manage to win four years ago, and what would it take for them to do it again on Apr. 16?

When the 2015 campaign began, Jim Prentice's PCs looked vulnerable. But their chief rival appeared to be Brian Jean and the Wildrose Party, not the NDP. The polls were looking promising for the New Democrats, but the party was only thinking about winning a dozen or so seats at the outset.

Instead, the NDP won a majority government of its own, securing 54 seats. Wildrose formed the Official Opposition with 21 seats, while the PCs were relegated to third party status.

On the latest episode of The Pollcast podcast, host and CBC polls analyst Éric Grenier chats with Sally Housser, press secretary to Rachel Notley during that campaign, about what it was like to be part of such a memorable election and the challenges the party faces today.

Then, Éric and the CBC's Elise von Scheel chat about the latest polls in the province and what to watch for between now and election day.

Listen to the full discussion above — or subscribe to the CBC Pollcast and listen to past episodes of the show.