Big numbers, murky logistics, and the emerging battle for the 'hearts and souls' of Alberta's UCP

Twenty thousand.

That's the estimated number of people the United Conservative Party (UCP) executive says could descend on the upcoming leadership review of Premier Jason Kenney. It could end up being thousands more.

It's a number no one has been able to explain and one that's causing headaches for every group involved — Kenney's campaign team, the party executive, the constituency associations and those trying to oust the premier. 

Kenney's team says it's perplexed by the registration numbers, currently at 15,000, and by who has registered for the vote on April 9 in Red Deer. 

According to their data, 49 per cent of those 15,000 bought their first UCP membership in the last four months.

"It's very unprecedented. I've never seen anything like it," a Kenney campaign official said. CBC News has agreed not to name them because they were not authorized to speak publicly about the review.  

"The liability is those unknowns."

Kenney's campaign estimates with those high registration numbers and a lot of uncertainty about event logistics, it could be a close result.

The premier has set the bar for success at a simple majority, 50 per cent of the vote plus one. It's the lowest possible margin of victory by the party's governance rules and a much lower goal than is typical (former premiers Ed Stelmach and Alison Redford both secured 77 per cent in their reviews and ultimately didn't finish their terms).

The party executive is discussing how to adjust the event logistics, with a decision expected this week. The party was planning the event for 3,000 people, not almost seven times that number. 

Party president Cynthia Moore originally insisted to the membership that a single, in-person location in Red Deer was the best way to ensure the fairness and integrity of the vote. With attendance ballooning, the party has been forced to consider other options. 

But a chunk of the party's membership is insisting the rules don't change. 

Thirty-three constituency presidents from across the province sent a letter Tuesday to the party president after a meeting Monday night, setting out their expectations for the logistics of the leadership review. CBC News obtained a copy of the letter.

They asked that the event remain in Red Deer, at the same venue on the same date as the party originally scheduled.