CANADEM executive director Paul Larose-Edwards told CBC News the organization is "very disappointed" that they won't be involved with the bilateral mission.
"We successfully deployed the 500 observers in 2004, and fully ran the missions in 2010, 2012, and 2013," he noted — all, he says, to "rave reviews."
This time around, however, that job will go to Canadian Election Observation Missions, or CANEOM, a newly-created group affiliated with the Forum of Federations, an Ottawa-based international organization.
While primarily focused on international governance issues, Forum has been looking into ways to "diversify its business line," according to its president, Rupak Chattopadhyay.
"For a while, we've been investing in building up capacity to do election monitoring," he told CBC News.
"So we put in a proposal for the Ukraine mission, and that's how we got into this."
In Ukraine, he explained, "'federalism' is a fraught word these days," which is why the more neutral-sounding CANEOM was set up.
CANEOM is also supported by volunteer-based development group CUSO International, as well as the Ukrainian Canadian Congress, according to its webpage.
CANADEM still part of OSCE mission
Chattopadhyay says they were invited to bid on the upcoming mission several weeks ago, but declined to provide further details on the estimated cost for their successful bid, noting that such questions would be better put to the government, He noted the government would have an "envelope" for such efforts.
As yet, he said, the organization hasn't received any money, and he was unsure how much total funding would be provided.
Meanwhile, CANADEM, which bills itself as "Canada's civilian reserve," is still slated to take part in the main Organization for Security and Co-operation in Europe (OSCE) mission.
According to Larose-Edwards, a total of 150 CANADEM-affiliated observers will be on the ground in Ukraine — 15 long-term observers who are "already out there," and an additional 135 short-term observers who will be joining them soon.
On Friday, The Canadian Press reported that an internal government assessment on the 2012 Ukraine election concluded that Canada may have sent too many bilateral observers.
It also found that OSCE "was the 'most credible' organization to conduct election monitoring."
Both groups get funding
A spokesman for Foreign Affairs Minister John Baird was unwilling to answer questions on why the government chose to work with CANEOM instead of CANADEM in the upcoming vote.
"The government … is financially supporting the deployment of Canadian election observers through credible implementing organizations," Adam Hodge told CBC News.
"Both CANADEM and CANEOM received funding from the Government of Canada to do important election observation work in Ukraine."