Two high-profile Conservatives made major career announcements Thursday, ahead of an anticipated cabinet shuffle.

Leader of the Government in the Senate, Marjory LeBreton announced her resignation from the post, while Conservative MP Diane Ablonczy, Minister of State for Foreign Affairs, said she will not run for re-election.

“After almost seven and a half years, I have advised the Prime Minister of my intention to step down as Leader of the Government in the Senate,” LeBreton said in a statement, explaining that she plans to carry on as a Conservative senator.

"I intend to step up my efforts in support of meaningful Senate reform and also actively back the new strengthened rules we introduced regarding Senate expenses,” she said.

At 73-years-old, LeBreton is two years away from the mandatory retirement age.

Prime Minister Harper issued a statement of his own Thursday, thanking LeBreton for her years of service.

"From our first day in office through to today, Senator LeBreton has contributed her wise counsel, exceptional work ethic, and unrivalled institutional knowledge, and in so doing has made a tremendous contribution to our Government,” Harper said in the statement.

Ablonczy, meanwhile, was first elected as a Reform MP in 1993. In the last election in 2011, she was re-elected with 70.2 per cent of the vote in the riding of Calgary-Nose Hill.

In a statement, Ablonczy called her work as an MP a “challenging and rewarding job,” and vowed to remain hard at work for the rest of her term.

She said that although she had intended to keep her plans to herself until closer to the next election, her colleagues’ public career announcements put her and her staff “in an uncomfortable position.

I therefore think that, especially since others beside myself are affected, this is the appropriate time to announce that after serving twenty-two years I will be leaving the political arena in 2015.”

Ablonczy thanked the prime minister, her staff and “my wonderful and unselfish husband Ron,” who all “have been a big part of whatever I have been able to contribute to the common good.”

The prime minister had asked his MPs to notify him of their intentions for 2015 as he considers the team that will take his party into the next election. Earlier this week, another Alberta MP, Ted Menzies, said he would not be running for re-election. Last month, Fisheries Minister Keith Ashfield stepped down as he undergoes cancer treatment.

Other cabinet ministers who could choose to move on to other endeavours include Public Safety Minister Vic Toews and Environment Minister Peter Kent. Finance Minister Jim Flaherty has signalled he would like to remain in the job despite health problems.

New faces in the cabinet could include MP for Ajax-Pickering Chris Alexander and MP for Calgary Centre-North Michelle Rempel.

Alexander, a former Canadian ambassador to Afghanistan, had a high-profile role defending the government’s record on the beleaguered F-35 file, while Rempel has been a key government spokesperson as Kent’s parliamentary secretary.

Others who may receive a promotion are Ontario MP Dr. Kellie Leitch and Manitoba MP Candice Bergen.

Consultant and former senior Conservative staffer Keith Beardsley said the cabinet shuffle will be about bringing in “some younger members to sort of rejuvenate, to get the generational change started.”

But NDP Leader Thomas Mulcair said the cabinet exodus is a sign that the Conservative government is “quite tired.”

“I guess this is the ultimate attempt to hit the reset button, but we think it’s too little, too late,” he said.

With a report from CTV’s Richard Madan