Alison Redford has announced that she is stepping down as Alberta premier on Sunday night.

Redford, who has been dogged by questions about her leadership, made the announcement in the rotunda of the Alberta legislature at 6 p.m. MT. She will stay on as the MLA for Calgary-Elbow.

"Quite simply I am not prepared to allow party and caucus infighting to get in the way of building a better future for our province and for all Albertans and that is why I am announcing today that with a profound optimism for Alberta's future, I am resigning as premier of Alberta effective this Sunday evening," she said.

Redford, 49, became the province’s first female premier in October 2011 after winning the leadership of the Progressive Conservative party.

A lawyer, Redford was first elected to the Alberta legislature in 2008. She led the Tories to a majority in the April 2012 provincial election.

Redford's voice started wavering during her resignation speech when she thanked her supporters.

"To my volunteers, who have been a part of this incredible journey," she said. "Your support, your warmth, your passion for Alberta has been one of the things that has inspired me from day one."

Alberta PC party president Jim McCormick thanked Redford for putting "Albertans, Alberta and her party first." (CBC)

The announcement came just as Progressive Conservative riding association presidents in Calgary were about to vote on whether Redford had lost the confidence of the membership and should be asked to resign.

In a statement, party president Jim McCormick thanked Redford for her time as leader.

“Tonight, Alison Redford has put Albertans, Alberta and her party first. We thank her for her time as leader of the party and government," he wrote.

Redford's resignation comes three months after she received 77 per cent support in a leadership review.

Party the problem, Wildrose says

Wildrose leader Danielle Smith said the PCs, who have been in power for 43 years, are the problem. She believes that Redford set out to fix the party when she first became leader.

"What we witnessed during her short 29 months as premier is the clearest indication yet that the PC party simply can’t be fixed," she said.

"The problems with their party and their government run far too deep for one leader to change, no matter how noble their intentions are or how deeply they’re committed to them. The business of governing this province and leading it through its challenges will now once again take a backseat to the internal politics of the PC party as they will again change their leader to try and solve a problem that simply can't be fixed."

Calgary Mayor Naheed Nenshi says Redford's resignation as premier is a sign of what is wrong with the political process.

Nenshi says while he disagrees with some of the things she did, Redford was trying to do good things for the province as leader.

Calgary Mayor Naheed Nenshi told reporters outside old city hall that Redford was a good person who was chewed up and spit out by the system. (CBC )

"I want to remind people that this is also a human story," he said.

"It's about a real person. A good person. A person who loves this province and has worked hard and made incredible sacrifices for this place. And it's the story of a system that takes somebody like that, chews them up and spits them out."

Nenshi's sentiments were also echoed by Alberta NDP leader Brian Mason.

"The polls are bad for her and the government right now and that's what matters to the PC party is power," Mason said.

"I have to say I thought she was a very intelligent premier with her own vision ... on a day like today you kind of forget the reasons why this happened and you just feel kind of bad for the person and their family."

Liberal leader Raj Sherman says the Tories are once again facing instability in their leadership.

"I wish Premier Redford would have stayed until the next election but unfortunately her party didn't want her," he said. "I'm saddened to see a leader having to resign because of party infighting."

Spending questions

Redford's problems escalated last week when she announced she was paying back the entire $45,000 she spent on first-class tickets and a government plane to travel to South Africa for Nelson Mandela's memorial in December after weeks of refusing to do so.

The next day, Calgary-Foothills MLA Len Webber stepped down from the PC caucus, alleging that Redford treated people poorly and wasted taxpayers' dollars.

On Saturday, Redford met with PC party executives at a closed-door meeting in Calgary. Although she was given a standing ovation, Redford was also grilled and given a "work plan" to follow in order to continue on as party leader.

However, that did little to quell the discontent within the caucus. At least 10 Tory MLAs held a meeting in downtown Edmonton Sunday night to discuss the possibility of quitting the party and sitting as independents.

Only one MLA has stepped down since that meeting. Donna Kennedy-Glans, Calgary MLA and associate minister for electricity and renewable energy resigned from cabinet and the party to become an independent member.

Donna Kennedy-Glans resigned from the PC caucus and from Redford's cabinet on Monday. The Calgary-Varsity MLA now sits as an independent in the Alberta legislature. (CBC )

Kennedy-Glans cited the party's sense of entitlement and a move away from fiscal discipline as reasons for her departure.

After Redford announced her resignation, Kennedy-Glans said she felt sad for her.

"For somebody to, halfway through a term say, 'I can't do it' just makes me sad," she said. "And yet I'm grateful too that our ability to actually do change can work. It's hard though. We do it in a very harsh way and that's sad."

Edmonton MLA Steve Young, one of the people at Sunday's meeting, says Redford did the right thing by "removing that doubt, that fracturing, so we can come together, reset the culture and principles of our caucus and our party to move forward in the right direction."

Redford has faced other questions about her spending, including her use of a government plane to fly to an uncle's funeral in Vancouver as well as take her daughter and a friend on several trips.

She announced that she would repay $3,156 to cover the cost of those flights.

The search is now on for Redford's replacement. The PC party constitution requires that a selection be made within six months of a leader's resignation.