CBC News has learned former Edmonton mayor and Alberta PC health minister Stephen Mandel will run for the leadership of the Alberta Party.

Sources confirm Mandel will make an announcement Wednesday in Edmonton.

The rumour mill started Monday after Mandel posted a tweet for the first time since he lost his Edmonton-Whitemud seat in the May 2015 provincial election.

The tweet was a photo of an upside-down grain elevator with the date of Jan. 10, 2018.

Mandel served three terms as mayor of Edmonton between 2004 and 2013.

In the fall of 2014, he came out of retirement to serve as minister of health under former Progressive Conservative premier Jim Prentice. He became the MLA for Edmonton-Whitemud after winning the byelection in October 2014.

However, Mandel's time in provincial politics was short-lived. He lost his seat to NDP candidate Bob Turner in the May 2015 provincial election, which saw the Conservative dynasty defeated by the Alberta New Democrats.

Mandel will join independent MLA Rick Fraser, Calgary energy lawyer Kara Levis and Jacob Huffman in the Alberta Party race.

More candidates may announce this week prior to the party's Jan. 15 deadline.

Alberta Party members will choose a new leader on Feb. 27.