Liberal Leader Justin Trudeau says anti-abortion MPs already sitting in his caucus can run as candidates, but will still be expected to vote along pro-choice lines on any legislation regarding abortion.

This is the second time Trudeau has had to clarify his position since telling reporters on May 7 that anti-abortion candidates would have to "vote pro-choice" on any bills. He had said sitting MPs would be "grandfathered."

Trudeau was asked about his position after a P.E.I. newspaper quoted Liberal MP Lawrence MacAuley as saying he would be able to continue to vote in favour of putting limits on abortion.

Trudeau said he had been referring to the nomination process, which is different than the one that was applied to incumbent MPs, when he talked about the grandfathering.

"But the policy going forward is that every single Liberal MP will be expected to stand up for women's rights to choose," Trudeau said Wednesday.

Trudeau said he remembered the question put to him on May 7 as being about the threat of anti-abortion groups taking over what the Liberals bill as open nominations.

"And I answered why I was not worried that that was going to happen, because the green-light process that we have established makes it clear that all Liberal MPs, regardless of their personal views, would be expected to vote pro-choice," Trudeau said.

'Grandfathered in to a certain extent'

Trudeau was asked in early May whether abortion would be an issue on which he whipped his MPs, which means ordering them to vote the same way.

Trudeau paused, said the question was a tough one, and talked about how the party attracts people with different views before answering.

"I have made it clear that future candidates need to be completely understanding that they will be expected to vote pro-choice on any bills. The existing MPs who have been grandfathered in to a certain extent will be respected, to a certain extent, in their choices, but our position as a party is we do not open that debate," Trudeau said.

Some sitting MPs interpreted that to mean they could continue to vote their conscience if they're re-elected in 2015.

"He’s indicated that I can vote whatever way I choose. I’m, I guess, what you call grandfathered," MacAulay told The Guardian this week. "I have voted pro-life all the way through."

MacAulay later tweeted a clarification.

"I accept and understand the party position regarding a woman’s right to choose," MacAulay wrote on Twitter. 

"I understand that I will have to vote the party position should this issue ever come up in the House of Commons."

NDP Leader Tom Mulcair says all 98 MPs in his caucus are pro-choice. Prime Minister Stephen Harper says the Conservatives won't re-open the abortion debate while he is leader.