Mainstreet Research — which admitted to "big polling failures" after Calgary's recent municipal election — says it no longer plans to pursue legal action against Mayor Naheed Nenshi's campaign pollster for what it said were libellous statements made during the fall election.

READ THE LATEST | Mainstreet says Calgary election polling failures caused by 'perfect storm'

A lawyer representing Mainstreet wrote to Brian Singh in late November, requesting he retract online comments he made about the polling firm's surveys before the Oct. 16 vote.

Quito Maggi, president of Mainstreet, tweeted Monday morning the letter sent to Singh had been rescinded and he "apologized unreservedly to [Singh]."

A letter was sent by our lawyer to Brian Singh weeks ago asking for a retraction of comments suggesting we rigged polls. That letter has been rescinded and I have apologized to Brian unreservedly. This was my mistake, and mine alone <a href="https://twitter.com/hashtag/yyccc?src=hash&ref_src=twsrc%5Etfw">#yyccc</a> <a href="https://twitter.com/MainStResearch?ref_src=twsrc%5Etfw">@MainStResearch</a> <a href="https://t.co/JZ4U5FzudO">pic.twitter.com/JZ4U5FzudO</a> —@quito_maggi

But Singh, president of Calgary-based Zinc Tank market research, said Monday the tweet was the first he had heard of the letter being rescinded.

Maggi said he asked his lawyer on the weekend to rescind the letter.

"There's no formal rescinding of a letter, it's not like I can ask him to send it back to me. I told my lawyer [Sunday] to rescind the letter and that we were in no way going to seek legal action," Maggi said Monday in an interview with CBC News.

FTR, I have not received any formal rescinding of the original C&D letter yet. (Original attached: dated Nov 27 and received Nov 30). <a href="https://twitter.com/hashtag/yycvote?src=hash&ref_src=twsrc%5Etfw">#yycvote</a> <a href="https://twitter.com/hashtag/yycvotes?src=hash&ref_src=twsrc%5Etfw">#yycvotes</a> cc <a href="https://twitter.com/CBCCalgary?ref_src=twsrc%5Etfw">@CBCCalgary</a> <a href="https://twitter.com/PostmediaNews?ref_src=twsrc%5Etfw">@PostmediaNews</a> <a href="https://twitter.com/calgaryherald?ref_src=twsrc%5Etfw">@calgaryherald</a> <a href="https://twitter.com/calgarysun?ref_src=twsrc%5Etfw">@calgarysun</a> <a href="https://t.co/Vhvv1sHzW7">pic.twitter.com/Vhvv1sHzW7</a> —@BFSingh

Mainstreet predicted Nenshi defeat

Mainstreet — commissioned by Postmedia, the company that owns the Calgary Sun and Calgary Herald, to conduct polls — was criticized by political commentators as it released three polls in the weeks before the election predicting Nenshi would lose to a relatively unknown challenger, Bill Smith.

The polls suggested Smith was leading Nenshi by between nine and 17 points, with Maggi predicting on Oct. 7 the "near-certain election of Bill Smith" and adding he likely wouldn't be the only one to lose his seat in "this change election."

Instead, Nenshi won re-election to a third term as mayor by eight points. All 10 incumbent councillors were also re-elected.

Singh says Mainstreet trying to 'salvage a reputation'

The legal letter sent on behalf of Mainstreet to Singh warned that if he continued "to make … accusations or refuse to retract [his] previous statements publicly," the national polling firm "will be forced to take legal recourse for the damages inflicted."

"His criticism went beyond mode, methodology, wonky breakout to conspiratorial accusations, certainly insinuations," Maggi told CBC News in an interview conducted Dec. 6.

The letter concluded that Mainstreet "is sincerely shocked and embarrassed at the polling error that occurred" and does not wish to pursue legal action against Singh.

But Singh says he reviewed what he said during the campaign — and doesn't see anything libellous.

Singh told CBC News he viewed the letter as an effort by Mainstreet to "salvage a reputation", which he believes was damaged by releasing what turned out to be flawed polling results.

Singh insists his comments were within the "spirit of the dialogue that was going on" during the campaign.

"A little bit of feisty talk between pollsters is fairly typical, especially for those who are involved in campaigns," he said.

Controversy over Mainstreet's polling got personal

Singh was far from the only one to criticize Mainstreet's polls during the campaign — and much of the discussion between Mainstreet officials and political watchers became personal.

Maggi fired back at critics on Twitter, labelling his critics "tinfoil hat"-wearing conspiracy theorists.

He singled out Mount Royal University political science professor Duane Bratt, who had questioned Mainstreet's methods and stressed the company's predictions differed significantly from other polls.

Comparing Calgary election pollsters. Forum/CMES & AC/LRT picked mayor, Mainstreet (Postmedia) did not. <a href="https://t.co/d5J1oSmNMa">pic.twitter.com/d5J1oSmNMa</a> —@DuaneBratt

After long reflection, no <a href="https://twitter.com/quito_maggi?ref_src=twsrc%5Etfw">@quito_maggi</a> I do not accept your apology. I am not "cool." —@DuaneBratt

Sanctions from MRU, ban on media comments, public shaming, defamation lawsuit? I don't know what, if any, tool you would have used. —@DuaneBratt

Late in the race, the LRT on the Green Foundation — a non-profit citizens group dedicated to light-rail transit expansion in Calgary — released a poll that had Nenshi in the lead.

Then, in an unusual move, a group of academics opted to release partial results from a larger study they were conducting that included public polling of voter preferences in Calgary.

That polling, conducted by Forum Research, also suggested that Nenshi was leading Smith.

Maggi challenged Bratt's credibility. Mainstreet vice-president David Valentin told 660 News that he found a lot of behaviour from political scientists "quite shocking" and "quite appalling."

He said Mainstreet planned on "singling … out" political commentators who criticized Mainstreet after the vote. Maggi later apologized to Bratt. But Bratt did not accept.

After the election, Maggi conceded that personal comments he made during the campaign may have gone "too far."

But he insisted some of the criticism of his firm's polling data was unfounded and based on "false information."

Mainstreet and polling industry association have clashed

Mainstreet has faced other criticism in the past.

A year before the Calgary election, Mainstreet was involved in a dispute with the Marketing Research and Intelligence Association (MRIA) that led the two to part ways.

The polling industry association sanctioned Mainstreet for public comments it made about another polling firm and announced it was suspending Mainstreet's membership with the association.

But Mainstreet says it purposely let its membership lapse in November 2016.

The MRIA announced plans on Oct. 27 to conduct an independent inquiry into what went wrong with publicly released poll results in the Calgary election.

Right after the election, Mainstreet announced plans to conduct its own investigation into its polling methodology and communication surrounding those results.

Those results were released on Monday.