Alberta's Progressive Conservatives began voting Thursday on whether to support a plan to unite with the Wildrose under the proposed United Conservative Party banner.

Surrounded by a small crowd of supporters in his southeast Calgary campaign office, PC leader Jason Kenney cast his ballot on a laptop.

"I'm confident the results will reflect the will of the grassroots," he told reporters.

Kenney estimates more than half of his party's 50,000 members are currently registered to vote.

They have until 6 p.m. Saturday to cast ballots online or over the phone.

While some members have raised concerns about a possible shift to the right in a new party, Kenney says he's seen strong support for a unity vote.

"The best way to address those concerns is through their active involvement," he said.

But not everyone is happy with the voting process.

Shawn Pickett announced on social media Wednesday his resignation as the PC constituency association president for the riding of Red Deer North.

'Hostile takeover'

"I do believe it's been a hostile takeover," he said. "People don't realize there's a lot of channels. There's party channels and there's Jason Kenney channels and those are two separate channels. I believe there's one person in control and they're going to do whatever they need to do to push this referendum through."

Pickett says he was told by Kenney supporters how voting would work at least 24 hours before it was announced officially by the party.

"I just don't feel from what I've experienced before that there's any way the deputy returning officers are going to be able to control anything going on in the [voting] kiosks."

The PCs require a result of 50 per cent plus one to approve the unity plan while the Wildrose Party requires 75 per cent approval from its membership.

Wildrose members will be voting online and in person on Saturday in Red Deer and party leader Brian Jean says he's seeing strong support for a yes vote in his party as well, but adds he'll back this weekend's results.

"Whether it means co-operation, or going along, or unifying, it's up to them, and I will honour them as a leader should," he said.

Voting results are expected to be announced shortly after voting wraps up Saturday.