"We are disappointed and we are saddened," Prentice said of party's loss to the NDP, which ended the Tories' long stretch in power. "Certainly I made mistakes. And there can be no doubt that 44 years was indeed a long time. However, the sun will shine again."
Until his speech at Thursday night's annual leader's dinner in Calgary, Prentice hadn't spoken publicly since the May 5 vote, when he immediately resigned both his seat and the party leadership.
He said he takes full responsibility for the party's failure — the Tories came into the election with 70 seats and were left with only 10 when it was done. Prentice was widely criticized during the campaign for an unpopular budget and for going to the polls a year early.
"I accept responsibility for the fact that we were unable to convince Albertans of the merit of our plan," he told party faithful. "Ultimately the plan we put forward alienated both public-sector stakeholders who thought it too aggressive and Conservative voters who thought it not aggressive enough.
"The voters are always right and they have chosen a different path than we advocated."
It was a subdued audience. There were 1,550 tickets sold at $500 apiece for the event, but far fewer than that actually showed up Thursday night.
"This is obviously not an easy night for anyone," admitted Prentice. "It is especially difficult for me. I will carry those decisions and the electoral consequences of it for the rest of my life."
The former federal cabinet minister said he is done with public life but intends to stick around as a volunteer in years to come.
He acknowledged there is a need for changes within the PC party going forward.
"We must learn from this experience and make changes to our party," he said. "The public will never entrust a party that is preoccupied with its own internal matters and personalities at the very moment it should have only one concern, namely the best interests of the province.
"We have all learned a lesson. We will re-emerge. And when we do, we will be more humble, wiser and better grounded."
Interim PC Leader Ric McIver told the crowd he was not about to "sugarcoat" where the party stands.
"We're in the penalty box," he said. "You know how I can tell? Because when we sat on the player's bench there was a lot more of us around.
"The people of Alberta have spoken. We need to respect their decision. No one has a divine right to govern."
McIver issued an unflattering description of the job the Progressive Conservative party did in the lead-up to the election.
He said they were too quick to blame others and too slow to take responsibility for Alberta's "fiscal mess."
"We were too quick to raise taxes on Albertans and too slow to cut spending in our government," he said. "We were too quick to talk and too slow to listen. At times we were arrogant and complacent and we forgot how to apologize and mean it."
Follow @BillGraveland on Twitter
Also on HuffPost