Stephen Harper's controversial director of communications, Sandra Buckler, is stepping down from her post.

She had been in the position since February 2006, when she replaced William Stairs, shortly after the Conservatives won the federal election.

In an email, Buckler did not say why she resigned but that "now is the time for me to exit stage right from the Prime Minister's Office."

Buckler also wrote that her time in the post was an experience she would never forget.

"It was an honour and a pleasure to serve the Prime Minister of Canada," added Buckler, who recently underwent surgery for thyroid cancer.

Buckler has been a powerful figure in the Harper government, which has ruffled the media's feathers with how tightly it has controlled information.

CTV's Chief Political Correspondent Craig Oliver said while PMO's strict communication plan worked in the early going, both the media and Tory MPs grew frustrated over time.

"At one point a senior MP told me, 'There are at least 75 of us who asked to move her on,'" Oliver said.

Oliver said many senior cabinet ministers wanted to go before the media to explain department policies, but were told by the PMO's office not to.

Oliver said Buckler was known as "The Centre" by many in the government. Many ministers would cancel interviews to say "The Centre has said I can't do it," Oliver said.

"She has been very powerful," he added.

Many backbench MPs expressed frustration as well, as they were told not to do interviews, leaving their constituents wondering "Why don't I see you anymore?"

But Oliver said that Buckler's policy worked very well for Harper in the first year of his government. The government was largely inexperienced and Buckler kept tight control over the government's message, Oliver said.

Controversy

But over time, Oliver said, the PMO's image began to suffer, as it became more centralized and authoritative.

Buckler was at the centre of controversy in January when she told CTV News that the military did not inform the Tory government of a change in how it handled detainees in Afghanistan.

However, she retracted the statement shortly afterwards following heavy criticism from opposition parties and reportedly from top military officials.

Oliver said that with Buckler leaving, Harper has an opportunity to remake the PMO's image with the media -- something that won't be easy given the amount of hostility between the two.

Harper's chief of staff Ian Brodie, who will be replaced in July, said in an email that "he was saddened when Sandra told me a while back that she was thinking of leaving the PMO."

Brodie added that "For more than two years now, Sandra has led a government communications operation that has been focused and disciplined. She has been tough, loyal and effective."