The Conservative Party of Canada is asking Elections Canada to investigate whether the NDP violated the Elections Act by accepting union sponsorship at its June convention.

In a letter sent to Chief Electoral Officer Marc Mayrand last week, Conservative Party lawyer Arthur Hamilton says the New Democrats "prominently displayed" signs acknowledging sponsorships from several unions and a printing company for events held during the convention in Vancouver.

The Tories suggest the sponsorship violated Section 404 of the Elections Act, which prohibits unions from making contributions to Canadian political parties.

Hamilton includes photographs of various signs at convention events, including a sign for a fundraising dinner featuring then-NDP leader Jack Layton and Nova Scotia Premier Darrel Dexter that featured the logo for the Public Service Alliance of Canada.

The Conservative Party of Canada sent Elections Canada several photos of signage at the NDP convention in June that display logos of Canada's largest unions. Conservative Party of Canada

In an email to CBC News Sunday, Heather Wilson, the NDP's director for fundraising and membership, insisted advertisments at fair-market-value are allowed by the law, and that Elections Canada "is fully aware of this practice."

Wilson also hit out at the Tories over their long battles with Elections Canada during the "in-and-out" affair over party spending in the 2006 federal election.

"This is a bit rich coming from the in-and-out party," Wilson said. "All rules and regulations have been followed by the NDP. And unlike the Conservatives, we stay within both the spirit and letter of the law."

Historically, the labour movement has had significant influence over NDP party policy, including a 25 per cent carve-out during the last leadership race in 2003.

Next week, the party's federal council will meet to determine whether a similar weighting system will be used when the party elects a new leader next year.

The Vancouver convention marked the rise of the NDP to Official Opposition status following its historic gains in the May federal election and cemented Layton's status as chief.

Layton died of cancer in August at the age of 61.

Letter to the CEO Dated August 31, 2011 (2) (1)