Derek Fildebrandt, who used to speak for the Canadian Taxpayers Federation, will represent the Wildrose in the constituency of Strathmore-Brooks.
The riding's current MLA, Jason Hale, crossed the floor in December to join the Progressive Conservative government.
Fildebrandt says about half the riding's Wildrose supporters had walked away from the party when he launched his campaign, because they felt betrayed.
But he says 98 per cent of them have returned and new members have signed up.
Fildebrandt says the party’s biggest job in the next election — widely speculated to come this spring — will be to persuade voters they can still trust the Wildrose.