Alberta's Progressive Conservatives say more than 50,000 people have signed up to vote on a proposal to merge with the Opposition Wildrose to create a new right-of-centre party.

The party estimates about 18,000 people purchased memberships since a unity deal with the Wildrose was announced on May 18, PC Leader Jason Kenney said in a news release Thursday.

The deadline was Wednesday night.

"It's a terrific number. It's very encouraging. It's a significant increase over the numbers we had during the (recent) leadership campaign," PC association president Len Thom said in an interview Thursday.

"It just shows that this is an issue that Albertans care passionately about."

The membership guarantees the cardholder will be able to vote electronically over three days starting next Thursday.

The results are to be announced July 22, the same day the Wildrose announces the results of its unity vote.

A simple majority of PC members are needed to ratify the unity plan, while more than 75 per cent of Wildrose members have to sign off on it.

The Wildrose membership deadline has also passed. The party says more than 40,000 signed up to vote.

Wildrose Leader Brian Jean and PC Leader Jason Kenney have been criss-crossing the province in recent weeks trying to drum up support for the proposed deal struck in May 18.

Should it be approved, the newly formed United Conservative Party would hold a leadership race and the winner would be selected Oct. 28. A founding convention would be held after that.

Jean, Kenney and Calgary lawyer Doug Schweitzer have already announced they will seek the leadership.

A unity bid was announced by Kenney over a year ago. He says vote-splitting among conservatives must end to avoid another NDP majority government in the 2019 election.