Despite the last-minute surge in support for the Progressive Conservative Party that led premier Alison Redford to an improbable landslide victory in April 2012, her resignation as premier this week is the latest sign that the party’s four-decade run governing Alberta may soon come to an end.

Redford, who took office in October 2011, will resign effective Sunday, creating a scramble for the PC government to find a new leader and a new premier in Canada’s wealthiest and fourth-most populous province — also the home province of Canada’s Conservative prime minister Stephen Harper.

Deputy premier Dave Hancock will serve as interim premier for the next four to six months until the party chooses a new leader.

Redford stepped down after facing a revolt within her own caucus, most notably over a decision to attend the funeral late last year of former South African president Nelson Mandela:

The embattled premier has been facing down critics since early this year, when she expensed about $45,000 for a trip overseas for Nelson Mandela’s funeral.  For weeks, Redford ignored calls to refund the money, which many called an extravagant and unnecessary use of public funds.

In mid-March, Redford apologized and repaid the costs associated with the trip, but it appeared the damage was already done.  Critics lambasted Redford for what they called a sense of entitlement as more revelations of questionable spending were brought to light, including allegations that Redford had flown on her own government plane while Progressive Conservative MLAs took half-empty flights to the same destinations.

Redford’s decision also follows a Leger poll earlier this month that showed her party trailing the even more socially and economically conservative Wildrose Party by a margin of 38% to 25% (the provincial Liberal Party would win 16% and the provincial New Democratic Party would win 15%).  More ominously, the poll gave Redford a 20% approval rating, compared to a 64% disapproval rating.  Other polls show the PCs trailing by an even wider margin — a March 19 ThinkHQ poll gave Wildrose a 46%-to-19% advantage.

MLA Len Webber broke from the PC caucus last week to stand as an independent, and Donna Kennedy-Glans did the same on Monday, with other PC legislators promising to follow.

The Wildrose leader, Danielle Smith, remains controversial, even within Alberta, a province with some of Canada’s most conservative voters.  But the uproar over Redford’s spending decisions plays right into the message of fiscal restraint that Smith has hammered since becoming the Wildrose leader in 2009.

Redford herself was always a bit of an outsider within the PC establishment, which has controlled Alberta’s government since 1973.  Ralph Klein, who died last year, became the face of prairie conservatism in Canada, and virtually synonymous with Alberta, while he served as premier between 1992 and 2006.  But his party began having troubles almost immediately after Klein left office.  Wildrose formed in 2007 in opposition to Klein’s successor, Ed Stelmach, who stepped down in 2011 following criticism over Alberta’s economic downturn in 2008-09 and the province’s first budget deficit for the first time in nearly two decades.

Redford, who was only first elected to the Legislative Assembly in 2008, widely trailed the establishment candidate, Gary Mar, through the first round of the PC leadership election — she  narrowly defeated him by a 51.1% to 48.9% margin in the second round to become premier, despite her caucus’s preference for Mar, a longtime minister in the Klein government and Alberta’s official representative to the United States between 2007 and 2011.  While Redford was Canada’s first female premier, Mar would have been Alberta’s first Asian-Canadian premier.

Polls in advance of the April 2012 provincial election showed the Progressive Conservatives in danger of losing badly to Wildrose.  But Smith’s controversial statements about climate change and comments about same-sex marriage from other Wildrose candidates gave Albertan voters second thoughts. Redford ultimately won 61 seats in the 87-member Legislative Assembly, though the Wildrose gained 13 seats for a total of 17 seats (the Liberals won five and the NDP four).

Theoretically, Alberta doesn’t need to hold a new election until June 1, 2016, and the Progressive Conservatives obviously hold a supermajority in the Legislative Assembly that they don’t want to lose anytime soon.  But there will be obvious pressures on Redford’s successor to call snap elections in light of Redford’s resignation, the government’s unpopularity, and the lack of an electoral mandate for Redford’s successor.  But you should expect that the new premier will hold off as long as possible given the wide poll lead for Wildrose — a snap election today would make Smith the next premier of Alberta.

The fallout is unlikely to harm the federal Tories, who have hedged their bets in the past between the PCs and Wildrose.  Alberta’s next election is likely to be a contest between the center-right and the populist right — many have compared Wildrose to the American tea party movement.

So who are the likely candidates to replace Redford as leader and,  ultimately, Alberta’s premier?

The frontrunner from within the PC caucus is probably finance minister Doug Horner, who has won plaudits for balancing Alberta’s budget for the first time since the financial crisis.  Other contenders from within Redford’s government include labour minister Thomas Lukaszuk, former municipal affairs minister Doug Griffiths and current municipal affairs minister (and former energy minister) Ken Hughes.

Former treasurer Jim Dinning, a top ally in Klein’s government in the 1990s, and the initial frontrunner to succeed Klein in 2006, could make another run for the leadership (he lost the leadership race eight years ago to Stelmach).

Mar, who has served as Alberta’s envoy to Asia since 2011, could mount another challenge as well.

Another possibility is Stephen Mandel, the former three-term mayor of Edmonton who stepped down in October 2013, who often clashed with the provincial government over budget cuts and education. 

Perhaps the strongest candidate is Jim Prentice, a longtime Harper ally, who served as Canada’s minister of Indian affairs, industry minister and environmental minister before retiring to the private sector in 2010.