Conservative leadership contender Tony Clement is dropping out of the race to replace Stephen Harper.

The Ontario MP said his campaign didn't raise enough money to meet the "financial realities of this race."

"I set for myself a series of benchmarks that I believed were necessary to achieve, by the fall, to ensure I had a viable chance of success," he said in a note to campaign supporters. "Unfortunately, we did not achieve those milestones to my satisfaction."

In a video posted to his Facebook page, the former cabinet minister thanked the "hundreds" of party members who had supported his run, but said he did not want to "expose my family to any further financial risk at this time."

Clement had already paid the first $25,000 instalment of the party's non-refundable $50,000 registration fee.

He had the public backing of just one current member of the Conservative Party's parliamentary caucus, Quebec Senator Leo Housakos, who told CBC News it was "far too soon to comment on endorsing another candidate at this point."

"I can tell you that I will be looking for the same qualities I always do in the leader of the [Conservative Party of Canada], the qualities I saw in Tony that earned him my endorsement — responsible, experienced and a proven leader," the former Senate Speaker said.

Clement, 55, said he would now turn his attention to serving interim leader Rona Ambrose and returning to the party's shadow cabinet in the House of Commons. "I will find another way to help both my party and our country."

He served as the party's foreign affairs critic before stepping aside to run for the leadership in July. (Candidates cannot serve in the Conservative's shadow cabinet.)

The Parry Sound-Muskoka MP has not yet endorsed another candidate.

"We as Conservatives are blessed to have such a deep and diverse group of individuals seeking the leadership. I, like every member of our party, am excited to remain part of that process," he said.

The federal Conservative Party will elect its new leader on May 27.

The contenders, so far

Candidate who has declared, registered and paid the full fee: Michael Chong.

Candidates who have declared and registered: Maxime Bernier; Kellie Leitch; Deepak Obhrai; Andrew Scheer; Brad Trost.

Potential candidates who have declared only: Dan Lindsay; Pierre Lemieux; Adrienne Snow.

Expected to declare soon: Erin O'Toole; Chris Alexander; Steven Blaney; Andrew Saxton.

Others who have mused about running but not declared: Kevin O'Leary; Rick Peterson; Lisa Raitt

2nd run at leadership

This was Clement's second run at the party's leadership. In 2004, he placed third behind Harper and Belinda Stronach.

Clement's political career began at University of Toronto, where he was president of the campus Progressive Conservatives.

He later worked as a staffer to former Ontario premier Mike Harris, where he helped to draft the so-called Common Sense Revolution, a series of policies pitched as a way to shrink the size of the provincial government and lower taxes after Bob Rae's time as NDP premier.

The U.K.-born Clement was then elected to Queen's Park in 1995. He held a number of cabinet portfolios under Harris before the ruling PCs were voted out of office in 2003.

He ran for leadership of the Ontario PCs but was ultimately bested by Ernie Eves.