Wildrose won the second-most seats in the last election, but its caucus fell to just five seats last week after nine of its MLAs, including leader Danielle Smith, jumped to the Progressive Conservatives.
Veteran MLA Heather Forsyth was named yesterday as the interim Wildrose leader.
The Liberals, who also hold five seats, have made a pitch to become the Official Opposition.
Wildrose's house leader, Shayne Saskiw, said Monday he has sent a letter to the speaker, Gene Zwozdesky, saying his party should keep its current opposition role.
"All precedents that are available out there clearly indicate in a situation like this that the existing Official Opposition retains that status provided they have a leader," Saskiw said. "And we now have a leader, and a very good one, so we expect a ruling tomorrow."
The benefits of being the Official Opposition include a higher salary for its leader, greater funding for research and the ability for party MLAs to ask more questions of the government.
Wildrose president Jeff Callaway said Monday the party will soon decide how — and when — it will choose its next leader.
"We've got 15 days from the date of the resignation of the leader to announce that we'll be having a leadership race, so that's early January, Jan. 2," Callaway told CBC News.
"We have 36 days to announce the actual process of how that will happen, and that'll include the concluding date and, per our constitution, we've got three to nine months from when that will happen. So it will be the conclusion of a process sometime between mid-March and mid-August."
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