If you watched Game 5 of the NBA Finals in Canada, you might have seen a 30-second ad from an organization called Engage Canada attacking Conservative Leader Andrew Scheer.

Where did the group get the cash to pay for a Toronto Raptors playoff commercial that could cost upwards of $50,000? The group is hesitant to say.

Tabitha Bernard, a spokesperson for Engage Canada, said in a written statement that the group’s ad campaigns are meant “to fight back against the dominance of corporate interests” on the airwaves.

The ad that ran during Monday night’s Raptors game accuses Scheer of “hiding something” and says that, if elected, he “would follow Ontario Premier Doug Ford” when it comes to health care and education cuts.

The group describes itself as a “grassroots organization.” Corporate records and archived union documents show that it is comprised of veteran political strategists and individuals with strong ties to some of Canada’s largest union groups.

Formally created in December 2014, according to incorporation documents, Engage Canada orchestrated a targeted ad campaign against Stephen Harper in the lead up to the 2015 federal election.

Using the tagline “Not There For You,” the group released several TV advertisements criticizing Harper’s tenure as prime minster.

“With the Conservatives, you and your family just aren’t in the picture” said one Engage Canada TV ad focused on income inequality. “The Harper Conservatives, they won’t be there for you,” said another focused on health care.

But Engage Canada was nowhere to be found on Election Canada’s list of registered third party advertisers as part of the 2015 election.

Engage Canada spent all of its advertising dollars before the election was called, meaning the group never had to register as a third party advertiser and disclose any financial details.

It looks like the group may be employing the same strategy this time around with Scheer, said Erin Crandall, an Acadia University professor who studies Canadian election law.

“If Engage Canada takes the same approach as the 2015 election, to stop advertising before the regulatory period, then we’re not going to have any insight into donors” said Crandall.

Engage Canada also used social media channels to bypass election advertising regulations in the last election cycle, said Crandall.

“If you can do all the big ad spending before the regulatory period, and then stick the ads up on social media where it doesn’t cost anything, then you’ve been able to strategically spend more than you would have been able to otherwise,” she said.

Monday night’s Raptors game is a prime example. Any and all production costs tied to the ad, and the price of the highly-coveted NBA finals airtime, do not need to be released by the group.

Since the ad money is being spent before pre-writ period, Engage Canada does not need to disclose any financial details.

And, short of Engage Canada releasing its own financial documents, it’s next to impossible to know where, exactly, the money to fund the group’s TV, radio and social media ads is coming from. Engage Canada told CTV News it is “funded entirely by donations, large and small, from individual Canadians, organizations, and groups across the country…including labour unions."

Two current directors of the group, corporate records show, are political campaign veterans Kathleen Monk, former campaign director to Jack Layton, and Dave Gene, former deputy chief of operations to Dalton McGuinty.

Monk confirmed she and Gene are active directors of the group in an emailed statement.

As of May 25, days before Engage Canada launched its anti-Scheer ad campaign, the group gained two new directors: Peter Kennedy, former Unifor national secretary-treasurer, and Igor Delov, executive assistant to the Provincial Building and Construction Trades Council of Ontario.

Unifor national president Jerry Dias asked union members to donate to Engage Canada during a speech made at a Unifor Ontario Regional Council meeting in December 2015, archived records show.

An executive member of the Provincial Building and Construction Trades Council of Ontario also asked their members to fund Engage Canada’s efforts.

“Partnering with Engage Canada, we could help reach more voters and defeat the federal Conservative government in the next federal election,” reads a 2015 letter from Patrick Dillon, business manager for the trades council, sent to the group’s many members.

When asked what relationship Engage Canada has with Unifor and other unions, Bernard said that “Unifor is one of many of Engage Canada’s donors.”

Bernard added that “it would be inaccurate to suggest that Unifor is our only funder” and acknowledged that other labour unions are financial donors to Engage Canada.

Bernard did not, however, elaborate on the amount that Unifor or other union groups have donated to the group in the past, or more recently.

Scheer and Unifor’s leadership have been publicly at odds recently due to the controversy surrounding the union group’s involvement in the panel to choose which news organizations will receive new tax credits.

The Conservative leader says that including an anti-Conservative union on the panel will undermine its credibility and give Prime Minister Justin Trudeau an edge in the upcoming election.

“Unifor is a highly partisan group with highly aggressive and partisan goals,” said Scheer during question period on May 29.

"Scheer puts the very principles of truth and democracy at risk with this own brand of fake news" said Unifor national president Jerry Dias in a written response to Scheer's comments.