Hillary Clinton likely alienated voters when she said on the campaign trail in September that half of Donald Trump’s supporters were “deplorables,” her campaign manager has finally acknowledged.

“I think it definitely could have alienated some voters, and that’s why she got out there right away,” Mook admitted reluctantly in a forum discussion hosted earlier this week by CNN’s Jake Tapper.

Tapper, who aired the segment on his show on Sunday, had asked the failed campaign chief about an internal Clinton campaign study which found that Clinton’s Sept. 9 comment that “you could put half of Trump’s supporters into what I call the basket of deplorables” had a more negative impact on undecided voters than anything else during the campaign.

In the CNN forum, which was also attended by Trump campaign manager Kellyanne Conway, Mook first downplayed Clinton’s remark.

“Did you realize at that time that that comment that she made was as potentially damaging as this one study by somebody who worked for our campaign says it was?” Tapper asked.

“Hillary apologized right away after that and said that she misspoke and that she regretted the comment. That’s something that Donald Trump wouldn’t do, you know,” Mook said.

But pressed by Tapper, Mook finally said that Clinton’s comment, which she made at an LGBT function, was alienating for some voters.

WATCH:

The internal study that Tapper cited during the forum was conducted by Diane Hessan. She was hired on special assignment by the Clinton campaign to help understand undecided voters.

[dcquiz] In an op-ed in the Boston Globe, Hessan wrote that she made contact with 300 undecideds and kept in touch with 250 throughout the campaign.

After Clinton’s loss, Hessan said that she reviewed all of her notes given to her by the undecided voters.

“All hell broke loose,” she wrote of her sample’s response to Clinton’s “deplorables” comment.

She relayed comments from a participant named George who lives in Pennsylvania, which Trump narrowly won.

“George told me that his neighborhood was outraged, that many of his hard-working, church-going, family-loving friends resented being called that name,” Hessan wrote in the op-ed. “He told me that he looked up the word in the dictionary, and that it meant something so bad that there is no hope, like the aftermath of a tsunami. You know, he said, Clinton ended up being the biggest bully of them all.”

Hessan’s findings undercut the theory floated by Mook and other campaign alums that FBI director James Comey’s actions leading up to the election led to Clinton’s defeat. Mook has blamed Comey’s decision to send letters to Congress pertaining to the FBI’s Clinton email investigation for hurting the candidate at the polls.

While Mook now realizes that Clinton hurt her electoral chances with the “deplorables” remark, he embraced it himself during the campaign.

“I think a lot of the people that stand by Donald Trump are deplorable. And the things that they say are deplorable,” he said during an interview with NBC’s Chuck Todd in October.

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