A Conservative MP's support for an e-petition calling for a semi-automatic rifle to be reclassified as a non-restricted firearm in Canada is in the spotlight, after a similar firearm was used in Sunday's massacre at a night club in Orlando, Fla.

Some 25,000 Canadians have signed the e-petition urging the Liberal government to reclassify the ArmaLite-15 — more commonly known as the AR-15 — to allow it be used in hunting. Owners of an AR-15 would still have to register with the RCMP and license the weapon.

U.S. authorities have identified the weapon used in the Orlando shooting as a Sig Sauer MCX rifle — which, like the AR-15, is a semi-automatic rifle and faces similar restrictions in Canada.

Bob Zimmer, the MP for Prince George-Peace River-Northern Rockies, said in May he was honoured to present the petition from the Lawful Firearm Owners of Canada, and urged Public Safety Minister Ralph Goodale to make the necessary classification changes.

"I support it because, essentially, a semi-automatic long-arm should not be restricted, and that's the essence of the petition," Zimmer said in an interview with CFRA, a local Ottawa radio station. "Firearms should be normalized, to a certain extent. We understand that they can be operated safely, and they're operated safely in Canada year after year after year, especially with our rigorous licensing regime, and the like."

"The AR-15, when handled safely, is a completely innocuous firearm," Zimmer said. "We support its reclassification back to non-restricted."

AR-15-style firearms have been the weapon of choice in many of the recent mass shootings in the U.S., including the Sandy Hook elementary school shooting and the Aurora, Col., theatre massacre.

The perpetrators of those shootings had access to large capacity magazines, which are not permitted in Canada, where magazines for semi-automatic rifles are legally limited to just five cartridges.

Zimmer refused to answer media inquiries about his support for the e-petition Tuesday.

Other Conservative MPs were also reluctant to weigh in on the policy stance, although foreign affairs critic Tony Clement said he was "not going to condemn" Zimmer for presenting a routine petition in the House of Commons.

'No reason whatsoever' to reclassify

Goodale said Tuesday he saw "no reason whatsoever" to reclassify the AR-15, even though the e-petition has amassed more signatures than any other since the introduction of this mechanism last December.

"We said clearly in our platform that we felt decisions of this nature were best made by the experts in the RCMP. They have designated this weapon as a restricted weapon and that seems to be a pretty compelling case," he said in the foyer of the House. "They should not be second guessed politically."

Brandon Smith poses with his AR-15 rifle during a pro-gun and Second Amendment demonstration outside the Arizona State Capitol in Phoenix. (Joshua Lott/Reuters)

The Liberal election platform pledged to reverse changes made by the former Conservative government in Bill C-42 last spring, which removed some of the paperwork and penalties around gun licensing and transportation and gave cabinet decision-making power over how guns are classified.

Newfoundlander Marc Bennett, the man who initially launched the e-petition, lamented the effect the shooting was having on his bid to reclassify the firearm. "[The shooter's] choice of weapon was unfortunately the firearm that I am trying to get derestricted in Canada," Bennett said in an interview with CBC News. "My initial reaction to it was, 'Oh my God,' like, you know, they had to use that firearm within the month that my petition was to be sent to the House of Commons for an answer from the government to see if they would allow that," he said.

'Horrific that such weapons exist'

Despite those restrictions, opposition MPs slammed Zimmer's proposal to loosen the rules around the AR-15.

"I think all Canadians are wondering why it's legal anywhere to sell AR-15 weapons. It is horrific that such weapons exist," Green Party Leader Elizabeth May told reporters Tuesday. "It was shocking to realize that he had presented that petition."

May said Zimmer should rethink supporting the e-petition in light of the Orlando shooting. She also said the AR-15 is a firearm that is wholly inappropriate for hunting.

"People who are legitimately hunting use a rifle, skill and aim. People don't go into the woods, loaded with AR-15s, hoping to blow wildlife to bits. They're hunting, they're not murderously slaughtering."

Gun enthusiasts look over Sig Sauer guns at the National Rifle Association's annual meetings and exhibits show in Louisville, Ky., on May 21, 2016. (John Sommers/Reuters)

Murray Rankin, the NDP's justice critic, said he was "very disappointed" to see such a petition come forward.

"I know at the time [Zimmer] made positive remarks. I hope he's reconsidered those remarks by now," Rankin said of Zimmer's vocal support.

Rankin also criticized the former Conservative government for changing regulations around firearms, which gave cabinet the right to overrule RCMP specialists on classifying firearms.

"We have to repeal the legislation that gives cabinet the right to make political decisions about which guns are available in Canada," he said.