Mayor Jim Watson says he's "disappointed" that local Conservative candidates have again snubbed Ottawa City Hall, this time by refusing to participate in an all-parties' debate next week.

The Oct. 5 debate was supposed to include one local candidate from each of the four major federal parties.

But a spokesperson for Mayor Jim Watson's office said Monday that the only Conservative to respond to an invitation by last Friday's deadline was Kanata-Carleton candidate Walter Pamic, and that was to decline.

"This is a city-wide debate, the other three parties are looking forward to it, and it was an opportunity for all parties to explain their plans for our city. So I think it's a missed opportunity on the part of the Conservatives," said Watson.

The spokesperson said candidate Pierre Poilievre's campaign had already warned the city no Conservative candidate would attend the debate. Poilievre couldn't immediately be reached for comment Monday.

Busy with door knocking, other debates

Local Conservative campaigns reached by CBC Ottawa Monday said their candidates were either busy knocking on doors or had prior arrangements on Oct. 5.

Conservative candidate Pierre Poilievre had already warned the city that no Conservative candidate would take part in an upcoming Oct. 5 debate. (James West/Canadian Press) Ottawa West-Nepean Conservative candidate Abdul Abdi had "another commitment" on the same day as the all-candidates debate, while Ottawa-Vanier's Conservative candidate David Piccini's time was better spent meeting constituents on their doorsteps, spokespeople for the two campaigns said.

Royal Galipeau, who has represented Ottawa-Orléans since 2006, is already appearing in six other debates, his campaign said Monday.

A spokesperson for Pamic — the only candidate to reply to the invite — said he would be "out in the community" as the debate comes just four days before advance polls open.

Debate refusal a 'bizarre move'

Watson said municipal projects like light rail and the Ottawa River Action Plan each have significant federal components and residents deserve to hear the full spectrum of opinions.

He called the Conservatives' unwillingness to participate a "bizarre move."

"The irony is that the Conservatives have had a good track record of supporting [those issues] after we've lobbied them on it. So I'm not sure why they couldn't find one out of nine candidates to come," Watson said.

Three other candidates will take part, however: the Green party's Jean-Luc Cooke, Liberal candidate Catherine McKenna and Emilie Taman for the NDP.

In August a briefing on municipal issues for local Conservatives had to be rescheduled when no candidates showed up. Only two candidates, including Poilievre, attended a second meeting with the mayor.

The other three parties sent all their local candidates to separate sessions.

All local candidates have also been invited to answer a questionnaire from Watson and the deadline for responses is Wednesday.