A Liberal candidate who expressed skepticism about the Sept. 11 attacks in the U.S. has resigned as the candidate in the B.C. riding of Cowichan-Malahat-Langford, CBC News has learned.

Maria Manna had posted comments on her Facebook page that questioned the official account of the Sept. 11, 2001, attacks, calling it "the lie."

Maria Manna and Justin Trudeau

'I fully support Justin Trudeau,' said former Liberal candidate Maria Manna in a statement explaining her resignation. (Maria Manna/Facebook)

On Friday, she defended the comments, made in 2010 and 2013, saying they were her "truth" at the time.

On Monday afternoon, she apologized and explained her decision to step aside on her candidate Facebook page.

"I fully support Justin Trudeau, the Liberal team and the real change they are bringing to Canadians," she wrote.

"This election is far too important to have my past opinions and comments detract from that goal."

New candidate named

In a statement, the Liberal Party said Manna's resignation was effective immediately, and that she'd been replaced as a candidate by Luke Krayenhoff.

"The Liberal Party of Canada is committed to ensuring the strongest representation for Canadians in communities across the country," said the statement.

Krayenhoff, who had previously sought the party's nomination in the riding of Esquimalt-Saanich-Sooke, said he started getting calls Saturday about replacing Manna.

"For myself, I'm just really excited about this opportunity to represent this riding," he said. "I want to see proper treatment of veterans, I want to see better transportation coming from up-island down to Victoria."

With three weeks left in the election, Krayenhoff said he would be getting help from Liberal Party headquarters to replace yard signs and distribute brochures about his candidacy.

The Elections Canada deadline for nominating a candidate was 2 p.m. local time on Monday.

Social media gaffes plague campaigns

Manna is just the latest in a series of would-be candidates embarrassed during the 2015 election campaign by earlier social media posts.

Another Liberal candidate in B.C., Joy Davies, left the campaign Sept. 10 after pro-marijuana Facebook posts came to light.

The NDP dropped its candidate in a Winnipeg riding last week after comments surfaced comparing an Orthodox branch of Judaism to the Taliban.

The Conservatives have also lost candidates, including a Toronto-area politician who posted YouTube videos of his crank calls, and a Newfoundland candidate who made comments on several social media platforms about women, abortion and racial minorities.

With files from Dan Burritt and Stephanie Mercier