Former leadership contender David Bertschi has been told he won't be allowed to seek the Liberal nomination in Ottawa-Orleans, clearing the path for one of Justin Trudeau's star recruits to carry the party banner in next year's election.

Retired general Andrew Leslie, an adviser to the Liberal leader on foreign policy, is now the only declared contender in the nomination contest.

Bertschi, who ran for the Liberals in Orleans in the 2011 election, emailed supporters Sunday informing them that his candidacy has been blocked and encouraging them to protest the decision.

He says he was given a number of reasons, which he didn't specify, but insists none of them are true.

However, Bertschi had been warned, along with other failed leadership contenders, that he would not be allowed to seek a nomination unless he could demonstrate significant progress reducing his leadership campaign debt of $150,000.

Leadership debt, failure to disclose defamation suit cited by party

Party insiders said Bertschi's debt was one of two reasons his candidacy was blocked.

The other involved his failure to disclose a defamation suit he launched in 2013 against an American gossip website but subsequently abandoned.

Bertschi says the decision, relayed to him in a letter from national campaign co-chairs Katie Telford and Dan Gagnier, is strictly designed to assure victory for Trudeau's preferred candidate.

"This was a purely political decision that came directly from the top and not from the designated chair responsible for the nomination of candidates colloquially known as the green light committee," he says in the email.

Bertschi started an online petition Sunday calling on the party to reinstate an open nomination process in Orleans.

"We urge all of you, irrespective of who you support, to make it clear to the Liberal Party of Canada that you want the Liberals of Orleans to pick the next candidate based on merit," he says in the email.

"Backroom, strong-arm politics are for other parties."

As of Sunday evening, just over 100 supporters had signed the petition.