Citing what she described as the "mean-spirited leadership" of the Conservative Party, Toronto-area MP Eve Adams has left the Conservatives to join the Liberal Party.

Adams announced her decision at a press conference in Ottawa alongside Liberal Leader Justin Trudeau.

Adams, who currently represents the riding of Mississauga-Brampton South, said in a prepared statement that she initially signed up to run for the Conservatives to improve the lives of Canadians.

Instead, she said, the government "is about to roll out policies like income splitting, which will devour the surplus without benefiting many Canadian families, or creating a single job."

"Even Canada's former finance minister, Jim Flaherty — a Progressive Conservative from Ontario — could not support the impact and the waste of income splitting," she noted.

As a result, Adams said, "I can no longer support mean-spirited leadership that divides people instead of bringing them together," she said.

"We need a kind, generous and strong leadership that champions shared vision for how to make Canada work for everyone."

That leader, it seems, is Trudeau.

Trudeau says Adams has 'passion' for job

Trudeau said he understood how "personally challenging" the decision was for Adams.

"She wanted to be her community's voice in Ottawa, not the prime minister's voice in her community," he said.

"She has shown passion and commitment to her constituents, both as a city councillor and as an MP, and in her work as a parliamentary secretary."

But, he said, she has also "seen her work restrained by a party focused on the politics of meanness and division."

Family '100% supportive'

Although Adams seemed to have no trouble outlining the issues that led her to leave the party that, she noted, she had supported since she was just 14 years old, Adams bristled when reporters asked how her decision had gone over with her partner, Dimitri Soudas. The former senior aide and onetime communications director to Prime Minister Stephen Harper also served as director of the Conservative Party in 2013.

"This announcement is about the fact that I'm leaving a party I faithfully served for 25 years," she said.

"My entire family is 100 per cent supportive."

When pushed, she suggested reporters were being urged to ask such questions by Conservatives.

"I know you wouldn't ask something like this," she said. "You wouldn't ask a woman what her spouse.... would be doing."

She also declined to address her well-publicized difficulties in securing a Conservative nomination in two separate ridings, which ultimately led her to announce that she would not be running for re-election.

Both Adams and Soudas came under fire last year during her ill-fated campaign to win the Conservative nomination in Oakville Burlington-North.

Last March, Soudas — who at the time was engaged to Adams — was forced out of his job as executive director of the Conservative Party over allegations that he had attempted to interfere in the race.

Eventually, the party put the nomination contest on hold. Both Adams and rival candidate Natalia Lishchyna subsequently withdrew last fall.

Liberal MPs were briefed on their new caucus colleague via teleconference on Monday morning. During that call, they were told that Soudas brokered the deal with the party, CBC sources said.

On Monday afternoon, Soudas tweeted that he "fully supports" Adams's decision.

"She is smart, hard working [and] caring," he noted.

Fully support <a href="https://twitter.com/MPEveAdams">@MPEveAdams</a>'s decision. She is smart, hard working & caring. —@D_Soudas

Later, Liberal spokeswoman Kate Purchase responded to the flurry of media speculation by tweeting that Soudas "will not have a formal role" with the Liberal Party.

"He, like her whole family, is supportive of [Adams's] decision," she added.

'Not about having a tough day at the office'

Adams said Monday her decision to join the Liberals "is not about having a tough day at the office."

"Everybody has grumpy bosses from time to time. This is about the fact that my values simply don't align with this team. I'd like to consider serving Canadians, and I believe Justin Trudeau and the Liberal Party offer the most positive, hopeful leadership available."

Adams intends to sit as a Liberal MP when the House reconvenes next week.

She also plans to seek a Liberal nomination in the Toronto area, although she declined to specify which riding she was considering.

Media reports have suggested she may take the plunge in Eglinton–Lawrence, currently held by Finance Minister Joe Oliver.

When asked about the prospect of going up against his former caucus colleague, Oliver pointed to Groucho Marx's famous observation, which, he said, could apply to Adams: "I wouldn't join any club that would have me as a member."

She said she sent Harper a letter informing him of her decision on Monday morning.

Harper's office declined to comment on the defection, referring reporters instead to the Conservative Party.

Wanted to run for Conservatives: Tories

In a written statement, Conservative Party president John Walsh said that "just a couple [of] weeks ago," Adams had requested permission to run for a Conservative nomination in a new riding — and was rejected.

"I informed her in writing on Jan. 29 that she would not be permitted to run for our party in the next election due to the misconduct from the Oakville North-Burlington nomination race," he said.

"I communicated clearly that our party takes our nomination rules and procedures seriously, and we made a commitment to run fair and open nominations, and any misconduct from candidates, including caucus members, would not be tolerated."

But in an email reply to CBC News, Purchase suggested the Conservatives were simply trying to discredit a former caucus member.

"Up until early this morning, she was a parliamentary secretary for the government and was being courted by senior members of the government to run in 2015," she noted.

Meanwhile, New Democrat Leader Tom Mulcair reminded reporters that his party has a "hard and fast" rule against admitting floor-crossers into caucus.

"What we saw today is the Liberals stoking cynicism ... by allowing someone who has supported Stephen Harper for the past nine years on every single decision he's taken," he said during a media availability at a Toronto brew pub to highlight his party's proposals to cut taxes for small business.

"All of a sudden, poof — she decides that she doesn't agree with herself, because she's the one who's been agreeing with Stephen Harper," he added.

He pointed to former Bloc Québécois MP Maria Mourani, who is continuing to sit as an Independent even after announcing her intention to seek an NDP nomination for the next election.

"The NDP would never allow anyone to cross the floor to join the caucus," Mulcair said.

"And I can guarantee you that we would never allow a Conservative, in particular, to ever join our ranks."

Albany Club cancels membership

Her decision to cross the floor has also cost Adams her membership in Toronto's tony Albany Club, CBC News has learned.

"The philosophy of the Albany Club is clearly stated in our prospectus, and is part of our culture," club president Scott N. Munnoch wrote in a letter sent to the former Conservative MP on Monday.

"It states: 'The exclusive social and business club for those who influence, celebrate, debate, and promote Canada's conservative and political history, ideals, values and leadership.' In light of your announcement today, please accept this letter as a termination of your membership."

Mobile users: Read the letter here.