What is preferential voting and how will it shape the UCP leadership contest?

One political scientist says the United Conservative Party's leadership vote result on Thursday night will come down to how many voting rounds need to occur under the preferential voting system.

What is preferential voting, and how does it work? Here's what you need to know.

Unlike provincial elections, which rely on a first-past-the-post system, the UCP bylaws call for leadership contests to use preferential ballots.

"In order to be elected leader, a candidate must receive over 50 per cent of the valid votes cast," the bylaws state.

Each ballot is worth one vote, but electors select the candidates in their order of preference, with the first choice being their most preferred candidate. Members can rank as many or as few candidates as they wish.

When tabulating results, should a leadership contestant receive more than 50 per cent of the total number of first-preference ballots cast, that candidate is the winner.

If no single candidate garners the required threshold, the contestant with the least amount of first-preference votes is dropped. Ballots for the dropped candidate are then redistributed to whomever those voters selected as their second choice.

That process is repeated until a candidate can meet the more than 50 per cent threshold.

Since seven candidates are vying for the position of UCP's top job, voters could select their order of preference for seven contestants, and there will be a maximum of seven rounds of voting, if necessary.

The UCP governance manual states the result of each round of voting should be publicly announced once completed.

In the unlikely event there is ever a tie, the UCP leadership election committee chair's ballot would be counted to determine which contestant is eliminated.

In Alberta, provincial elections use first-past-the-post, where electors select one candidate on a ballot, with the contestant who earns the highest number of votes being elected.

Under that system, the candidate with the most votes can win, which can often mean they are elected without an absolute majority.

'NEVER RULE OUT UNPREDICTABLE THINGS'

Political scientist Chaldeans Mensah described the preferential ballot system as a "tricky system" that can create surprises depending on which candidate is dropped after the first ballot.

"Never rule out unpredictable things to happen with the preferential ballot system," Mensah said. "Everything depends on who gets dropped out of the count in the first ballot."

For this contest, Mensah, with MacEwan University, believes it will ultimately result in a two-horse race between Danielle Smith and Travis Toews.

"If she doesn't do so well on the first ballot, then that sets up the potential for someone to come from behind," he added.

"If it's a short contest, maybe one, two, three rounds, I think Danielle Smith will likely win it."

Five other people are running to lead the UCP and become premier-designate of Alberta: Brian Jean, Rebecca Schulz, Rajan Sawhney, Leela Aheer, and Todd Loewen.

The new leader is expected to be announced after 7:30 p.m.

With files from CTV News Edmonton's Diego Romero