NDP MPs will never vote against a woman’s right to choose, says the party’s leader Thomas Mulcair, who is also making clear that anti-abortion candidates are not welcome to run for the party.

Mulcair made the comments after a speech in Quebec on Thursday. He was asked by a reporter whether his party “writes off” voters who are anti-abortion, thousands of whom were on Parliament Hill Thursday at the annual March For Life.

The NDP believes that “it’s not debatable, it’s not negotiable, it is a woman’s right to determine her own health questions and her own reproductive choices,” Mulcair said.

The NDP caucus will never include MPs who are anti-choice, he added.

“In the NDP, no MP is ever going to vote against the woman’s right to choose. No one will be allowed to run for the NDP if they don’t believe that it is a right in our society for women to make their own choices on their reproductive health. Period.”

On Wednesday, Liberal Leader Justin Trudeau said his party will not accept anti-abortion candidates, although current Liberal MPs who are anti-abortion can remain in caucus, he said.

“It is not for any government to legislate what a woman chooses to do with her body, and that is the bottom line,” Trudeau told reporters on Parliament Hill.

After Trudeau made his announcement, Toronto-area Liberal MP John McKay, who is anti-abortion, told CTV’s Power Play that every MP has “difficulties with his or her party from time to time, and I guess this is my day.”

His views are well-known on Parliament Hill, he said, adding that he “errs on the side of life” in the case of a fetus, as well as when considering issues such as end-of-life care and capital punishment.

McKay, who has been the MP for the riding of Scarborough-Guildwood since 1997, has already secured the Liberal nomination for the 2015 election. Under Trudeau’s new policy, McKay will be allowed to run again as a Liberal.

Alissa Golob, the youth co-ordinator of the Campaign Life Coalition who was in Ottawa Thursday for the annual March for Life rally, told CTV’s Power Play she’s not surprised by Mulcair’s statement because the NDP “have always been the enemy of the pro-life movement.”

But Golob said it’s “shocking” to her that Trudeau is “forcing his caucus to completely ignore logic and science and abide by the gospel according to Justin.

“He says on one hand that he welcomes voices of all different points of view, but on the other hand he says: ‘except half the country who disagrees with abortion.’”

Joyce Arthur of the Abortion Rights Coalition of Canada disagreed, saying that the vast majority of Canadians support keeping abortion legal.

Arthur said barring anti-abortion candidates is a “great move” for the Liberals, “a natural progression of a party that respects human rights.”

Because making abortion illegal would infringe on women’s fundamental Charter rights, “this debate is long over,” Arthur told Power Play.

“We really should not be talking about it, at least not in Parliament.”

Meanwhile, thousands of people, and several Conservative MPs, gathered on Parliament Hill for the annual March for Life.

While the annual demonstration is peaceful, pro-choice protesters tried to disrupt the event, some shouting “my body, my rules.”