"Um. That is. Uh, uh, an issue that ... I've committed in my ... Well, it is a tough one," he said to reporters in the House of Commons, before getting into the groove of an answer that ultimately threw Parliament Hill-goers and members of his own party for a loop. ​

Trudeau said future candidates would be expected to vote pro-choice on any bills, and that "moving forward, the party that we're building ... will be resolutely pro-choice."

The announcement surprised a number of Liberal MPs and created a flurry of confusion within party ranks about whether anti-abortion candidates (including former Liberal MPs and cabinet ministers) would be excluded from the party in the future.

Several sources told CBC News that the Liberal leader's remarks were off the cuff and not as clear as they should have been. The party then clarified on Victoria Day that all personal views are welcome, but that incoming Liberal MPs must vote pro-choice.

Whether or not the declaration was originally a Trudeau slip, it's become a strategic move.

“I believe that what the Liberals are trying to do is lay track, so to speak, for the next election,” said pollster Nik Nanos of Nanos Research.

Nanos said that because the abortion debate is "a lightning rod" for many Canadians, Trudeau is bringing it up now so it doesn't look like the Liberals are "desperately pulling a rabbit out of a hat" in the midst of the election campaign.

At the same time, it's another indicator that the Liberal leader might be turning the page on the party, as previously evidenced by support for marijuana legalization and removing senators from the Liberal caucus.

The stark pro-choice stance is also a clear advance on traditional NDP territory. The Official Opposition's policy is to guarantee safe and accessible abortions.

"The New Democrats should actually be quite afraid," said Nanos.

What that means, he said, is if the next election is about who can beat Stephen Harper, then there will be people who will "reluctantly" vote Liberal even if they support the NDP because they are being "squeezed politically."

Though some Liberal sources said they're unsure if the move will result in a net gain or net loss for the party, Nanos believes this will be a Liberal gain in the long term. He said the issue of being pro-choice is not necessarily a major force because the more socially conservative Liberals would still have to "turn themselves inside out" to vote Conservative.

The NDP, however, brushed off election concerns, saying that they have "clearly" been a pro-choice party and one that stands up "unequivocally" for women's right to choose.

NDP status of women critic Niki Ashton compares that with what she calls the Liberals' "two-tiered approach" to women's rights.

"Confusion like what we’re seeing from the Liberals is not the way to attract voters, especially women voters,” said Ashton.

The Liberal Party is already touting the positives of the announcement.

"Since releasing his letter to the party membership on Sunday, 2,000 Canadians who had never interacted with the Liberal Party before have been in touch and over 10,000 Canadians have signed the petition," said Trudeau spokeswoman Kate Purchase in an email to CBC News.

But Nanos said there are still risks for Trudeau, who is branded as a "fresh-faced" leader engaging in a "different type" of politics.

That image could potentially be undermined if Trudeau looks to be a heavy-handed leader.

“He has to watch out that there isn’t a narrative that the Liberals are divided,” said Nanos.

What's important, he said, is how Trudeau manages discontent within Liberal ranks — something that afflicted former Liberal leader and prime minister John Turner.

“If party members aren't behind their own leader, how can Canadians be behind their leader?”