Bev Oda, the CIDA minister whose spending habits raised the hackles of the Harper government, announced she was quitting politics after insiders cautioned her she would not survive a cabinet shuffle, according to a source familiar with the matter.

The source said Ms. Oda, who's occupied a minister's post since the Tories took power nearly six 1/2 years ago, was informed she would be dropped as minister responsible for the Canadian International Development Agency when Prime Minister Stephen Harper rearranged his cabinet.

At 67 – she will be 68 in late July – the Ontario MP faced the prospect of sitting in the backbenches if she stayed on.

Story continues below advertisement

Her departure leaves Mr. Harper with a vacancy to fill and gives him an excuse to conduct a bigger overhaul of his cabinet. The size and timing of a cabinet shuffle has yet to be determined but one Conservative insider said it could take place in early August and may be smaller than expected.

The government admired Ms. Oda's performance at CIDA, but as with the ouster of former Foreign Affairs minister Max Bernier in 2008, she crossed a line and this led to her downfall.

Ms. Oda broke news of her departure on her website Tuesday, stating that she would be quitting as MP for Durham as of July 31. She gave no reason for her exit but revealed she'd informed the Prime Minister "two weeks ago" and thanked him for his leadership.

The CIDA minister came under fire in recent years for her use of limousines on the taxpayer tab but it was a pricey hotel upgrade – and the decision to spend $16 on a room-service delivery of orange juice – that blew up in her face this spring.

She came under heavy fire in the Commons and across the country after news broke that while attending a 2011 British conference on immunizations for poor children she'd rejected a five-star hotel in London in favour of booking the pricier Savoy Hotel at double the cost.

Ms. Oda was forced to apologize to the Commons over the lodging switch – a move that fellow Tories say was prompted by her desire to stay in a hotel that allowed guests to smoke in their rooms.

Conservative colleagues Tuesday described Ms. Oda as a solid minister but one who had a blind spot when it came to anticipating how the public might react to reports of lavish spending.

Story continues below advertisement

"She's no Marie Antoinette but she's just not sensitive to this stuff," one fellow MP said.

Said a senior Tory: "Some people have the ability to look down the road, and see how things will play publicly and then avoid the mistake. I don't think Bev had that filter."

The Tories won power in 2006 with a promise to stamp out "entitlement and corruption" and, ever mindful of this, Mr. Harper has limited patience for ministers who draw headlines for opulent expenses.

Ms. Oda's exit is different from that of Mr. Bernier and former Minister of State (Status of Women) Helena Guergis in 2010.

The Conservative government genuinely approved of Ms. Oda's record at CIDA. In their eyes, she made tough decisions. She refocused broadly dispersed multilateral aid to a more tightly targeted group of countries. She cut off or reduced funding for non-governmental organizations that the Tories didn't like.

The problem for the PMO is the "$16 orange juice" controversy refused to die down; the government found the affair was hurting its image.

Story continues below advertisement

As evidence of how estranged she'd become, just week ago Ms. Oda came under friendly fire from a fellow Tory MP who took the extremely rare step of attacking a colleague publicly.

In late June, Edmonton-area MP Brent Rathgeber used a blog post to lament the "extravagance" he felt was out of step with the values of ordinary Canadians – people, he said, who "have never ridden in a limo ... [or] ever drunk $16 orange juice" and would surely "appreciate it if government took more care in spending their money."

Mr. Harper made a great effort Tuesday to laud Ms. Oda's CIDA record after she announced she was leaving – an approach that significantly contrasted with how Mr. Bernier or Ms. Guergis were unceremoniously dumped.

"Under Bev's guidance, Canada has led a significant initiative to save the lives of mothers, children and newborns in the developing world. Bev has also promoted accountability and effectiveness for Canada's aid programs and has championed high-profile efforts to respond to humanitarian tragedies in Haiti, Pakistan and the Horn of Africa.," the Prime Minister said.

Because she's served more than six years as an MP and is over 55, Ms. Oda immediately qualifies to receive an MP's pension after she leaves.

The Canadian Taxpayers Federation, a fiscally conservative lobby group, estimates that Ms. Oda's annual parliamentary pension will start at $52,183, cumulatively reaching $701,464 in payouts by the time she reaches the age of 80.

Story continues below advertisement

"Bev Oda's lifetime pension should cover about 43,841 glasses of $16 orange juice," CTF National Research Director Derek Fildebrandt said.

Ms. Oda was first elected in 2004.

Charlie Angus, the NDP ethics critic, said Ms. Oda leaves with a "huge ethical cloud hanging over her head."

He said he feels it's unfortunate that Mr. Harper never intervened to publicly dismiss her, saying that would have sent a strong signal that the Conservatives value thrift and honesty among their cabinet ministers.