Former Conservative Eve Adams can count on the support of at least one card-carrying Liberal Party member at the Eglinton–Lawrence nomination meeting in Toronto on Sunday: her fiancé Dimitri Soudas, former executive director of the Conservative Party.

But because they live outside of the riding, Adams and Soudas count as associate members of the riding association, and neither can cast a ballot in her favour.

When Adams, a sitting MP, left a Conservative parliamentary secretary post to cross the floor to the Liberals in February, Soudas was coy about what it meant for his relationship with the party for which he'd worked for more than a decade.

Now, with Adams set to face off Sunday against long-time Liberal Marco Mendicino, CBC News has learned Soudas has bought himself a Liberal Party membership in Eglinton–Lawrence.

At one time, Adams was the parliamentary secretary to the health minister and Soudas was the executive director of the Conservative Party of Canada. Before that, Soudas had been a fixture in Prime Minister Stephen Harper's office, eventually becoming director of communications to the prime minister in 2011.

But Soudas was fired four months after being made head of the party over allegations he was helping Adams win the Conservative nomination in the redrawn riding of Oakville North–Burlington. After repeated allegations from both sides, the party postponed the vote, and eventually both Adams and rival Natalia Lishchyna gave up the race.

Seven months later, and after the Conservative Party denied Adams the chance to run for a nomination anywhere else, she crossed the floor and joined the Liberal Party caucus.

'Robust and exciting' contest

On Sunday, Adams will find out whether her efforts have paid off. In Mendicino, she's challenging a long-time Liberal who has sat on the riding association's executive and volunteered on a number of federal and provincial campaigns. Mendicino, a former federal prosecutor, also earned the endorsement of Mike Colle, a Liberal member of Ontario's government.

But a source in the riding said Adams has signed up 2,800 members versus Mendicino's 1,800. The Liberals have ensured experienced people will be running the nomination meeting in case of complaints from either side.

Our amazing team. Thank you for your long hours! <a href="http://t.co/mGxT7jpnOc">pic.twitter.com/mGxT7jpnOc</a> —@MPEveAdams

A separate source says more than 300 of the 4,800 members have been challenged by one side or the other. Both campaigns have raised problems with each other's lists. The national office have reviewed the complaints but the results haven't yet been released.

Adams declined to be interviewed, saying she is working hard to get out the vote. Mendicino was also unavailable (both offered to do interviews following the vote on Sunday).

An official from Adams's campaign said she has the endorsement of former Ontario Liberal cabinet minister George Smitherman, as well as the president of the Eglinton-Lawrence riding association.

Charles Bird, a spokesman for Mendicino, said he's been campaigning for the nomination for nearly a year. He agrees the dynamic changed when Adams entered what had been a one-person race.

"The benefit of having someone of the profile of Ms. Adams as your opponent is it tends to make for a very robust and exciting nomination contest. And in terms of heightening his profile in the riding and in the media generally, I think it's done wonders," Bird said.

Whichever person wins will take on Finance Minister Joe Oliver, the Conservative Party's nominee in the riding.

The vote is set for 2 to 6 p.m. ET Sunday.

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