NDP Leader Tom Mulcair hammered Prime Minister Stephen Harper over his pick for Canada's next privacy commissioner, a day before Daniel Therrien's appointment is expected to be confirmed.

Therrien, a longtime lawyer who currently works as assistant deputy attorney general for the Justice Department, will be vetted by MPs on Tuesday before he is confirmed by the Senate a few hours later.

The federal government has credited Therrien for crafting privacy rules governing the sharing of information under the Canada-U.S. Beyond the Border deal.

"Does the prime minister understand why Canadians find it more than a little bit creepy that the prime minister wants to name this guy to protect their privacy," Mulcair said during question period on Monday.

Harper defended his appointment saying Therrien was "a non-partisan public servant of some 30 years of experience, an expert in his field. He comes highly recommended ... we're convinced he will do a good job."

Mulcair also took a jab at Liberal Leader Justin Trudeau, who has indicated that he supports Therrien's nomination.

"Are the prime minister and his pal, the Liberal Party leader, really the only two people in Canada who don't understand this obvious conflict of interest," Mulcair said.

Treasury Board president Tony Clement, who recommended Therrien from a short list of two people, refused to comment on media reports Monday that said candidates more qualified than Therrien were overlooked for the job.

"We were blessed by having a half-dozen or more excellent candidates. My job was to choose the best candidate in the circumstances," Clement said.

He said any suggestion that Therrien isn't qualified for the job is "terribly unfair."

Cyberbullying bill

A number of privacy experts have raised concerns about the prime minister's choice for privacy watchdog.

In a letter to Harper, the experts called on the prime minister "to rethink his controversial" appointment because Therrien does not have "the perspective and experience necessary" to tackle issues of privacy.

"The lack of a strong privacy watchdog, particularly at this juncture when critical issues are being decided that will impact the privacy of Canadians for decades to come, is indefensible," the experts said.

The group of experts are also calling on Harper to remove online spying provisions from Bill C-13.

Neither the incoming or outgoing privacy commissioner will present their views on the government's controversial cyberbullying bill to a House of Commons committee on Thursday.

"We decided that appearing this week could be challenging," Valerie Lawton, a senior communications adviser for the privacy commissioner's office,​ told CBC News on Monday.

Neither Chantal Bernier, the interim privacy commissioner whose six-month term ends tomorrow, or the next privacy watchdog, who is being vetted tomorrow, will have an opportunity to give their views on Bill C-13. At least not in front of MPs.

"We are still considering our next steps. We could appear on the issue before the Senate or we could file a submission," Lawton said.