Raj Sherman of the Alberta Liberals announced Monday he was stepping down from the party's top job immediately and will not run in the next election in his riding of Edmonton-Meadowlark.
He joins three other former leaders who have already stepped down — Progressive Conservative premier Alison Redford, Danielle Smith of the Wildrose and Brian Mason of the NDP.
Sherman, 48, said that after two terms and three years as party leader, it was time to go.
"It's a personal decision for me," Sherman told a legislature news conference, alongside Liberal Party president Shelley Wark-Martyn.
"It's time for me to move on to new challenges, and to turn the page on the next chapter of my life."
Wark-Martyn said the party's board of directors will name an interim leader and map out the leadership race at a meeting in Calgary on Sunday.
She said it's up to the executive to decide if the party will have a permanent or interim leader should an election be called for this spring.
Under Sherman, the Liberals continued their decline in both fundraising and in popularity, dropping from 16 seats in 2004 to nine seats in 2008 to just five in the 2012 campaign.
Nevertheless, Sherman said he was proud of his accomplishments, saying he took the party out of debt and has all the riding associations registered and ready to take candidates.
"We offered the platform that would fix many of the problems Albertans faced," said Sherman.
He noted they fought for progressive taxation on income, something now being considered by Premier Jim Prentice.
Sherman said he will now spend time visiting his mother and his two college-age children and continue to work as an emergency room doctor.
During his career, Sherman cut a colourful and confrontational swath.
He was drafted by the Tories and won the Edmonton-Meadowlark seat under their banner in 2008.
He was named junior health minister but soon became estranged from his caucus, criticizing then-premier Ed Stelmach for failing to deliver on promises to fix health care and assailing health officials for "knucklehead'' decisions.
Kicked out of caucus, he sat as an Independent before joining the Liberals and winning the leadership in 2011.
Sherman's decision puts the Liberals in flux at a time of electoral uncertainty.
Conservative Premier Jim Prentice has not ruled out a spring election, even though the next contest is not scheduled by law until 2016.
The Tories, and other parties, are now fast-tracking candidate nominations.
Of the current five Liberal MLAs only two — Laurie Blakeman and David Swann — will run again.
Calgary Liberals Kent Hehr and Darshan Kang are running for the federal party.
Wark-Martyn said the Liberals will begin nominating candidates in February.
The Wildrose party is also holding a leadership race to replace Smith, who led a massive Wildrose floor-cross to the PCs before Christmas. Heather Forsyth of Calgary-Fish Creek is the interim leader.
The NDP's Rachel Notley replaced Mason, who stepped down last fall but stayed in caucus.
As the vote looms, resignations are adding up. Last week, former Tory cabinet ministers Doug Horner and Fred Horne announced their political retirements.
On Monday, former municipal affairs minister Doug Griffiths announced he was resigning from his Battle River-Wainwright riding immediately, saying it was time for fresh faces in the legislature.
Longtime Red Deer-North Tory Mary Anne Jablonski announced she will not run in the next election. Rookie PC backbencher Donna Kennedy-Glans said she will not stand for re-election in Calgary-Varsity.
Former Wildrose MLA Joe Anglin, who quit the party in November to sit as an Independent, said he will run for the PC nomination in his riding of Rimbey-Rocky Mountain House-Sundre.
Derek Fildebrandt, the former head of the Alberta chapter of the Canadian Taxpayers Federation, announced he will run for the Wildrose in the riding of Strathmore-Brooks.
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