"Wildrose is the only thing standing between Alberta and huge tax increases," leadership candidate Brian Jean told more than 150 party members at a campaign readiness forum.
"Just when people are hurting, just when the price of oil went down, just when there's layoffs, just when there's cuts, (the Progressive Conservatives') answer is to make you pay for their mistakes."
Prentice and Finance Minister Robin Campbell have said they are looking at personal income tax hikes along with increases to user fees and tuitions, as well as the return of health premiums, to pay for billions of dollars in lost budget revenue due to plummeting oil prices.
They have said oil royalties and corporate taxes won't be hiked.
Campbell has also promised five per cent department spending cuts across the board, and all MLAs have accepted five per cent pay cuts.
But candidate Drew Barnes told party faithful the Tories have lost the trust of the public to do the job because of years of wasteful spending.
"After 44 years of waste and entitlement, we have the most expensive government in Canada," said Barnes.
"Our PC government spent almost $2,000 per capita per year more than the Canadian average."
"(Albertans want) a government they can trust to operate a fair and ethical functioning democracy."
Prentice, in the context of spending, has called the wages of teachers, nurses, and other civil servants "unsustainable."
Candidate Linda Osinchuk, in her speech, called that policy self-defeating.
"The front-line workers need to be supported, not cut down," said Osinchuk.
All political parties have been scrambling to sign up candidates for an election call expected as early as late March.
Prentice all but confirmed this week the election was coming when he said the budget and long-term financial blueprint he will table next month will be so revolutionary, they will demand a "mandate" from Albertans to carry out.
Prentice has promised to remake the foundations of how the government raises and spends money so that day-to-day department budgets are not held hostage to the swings of oil prices.
The Wildrose leader will be announced March 28.
The race was called after former leader Danielle Smith and 10 other caucus members crossed the floor to Prentice late last year.
The candidates said the floor-crosses brought cynicism, anger and disillusionment but said the party is determined to forge that dismay into a steely resolve to stay alive.
However, the lingering anger was still evident Saturday.
Jean, in his speech, labelled Smith a "traitor" and "a betrayer of family."
Interim leader Heather Forsyth shook her head when reminded that Smith, the arch-fiscal conservative, took to Twitter this week to promote tax increases.
"Danielle will say what has to be said to get into cabinet," said Forsyth.
"She sold her soul as far as I'm concerned."
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