Appearing on "Fox & Friends" with host Ainsley Earhardt on Thursday, Carter said voter reaction for the tiff between the two outspoken 2020 Democratic candidates was mostly negative.
"You can see Democrats gave this a C, Independents a D, Republicans an F," she told Earhardt. "It wasn't necessary."
Carter, the president of Maslansky & Partners, broadcast her "voter dials," which assess the real-time reactions to the debate from voters across the political spectrum, rating candidates' statements from A to F.
In response to Gabbard's defense of characterizing former Secretary of State Hillary Clinton's leadership as the "personification of the rot that has sickened the Democratic Party," Harris said that if anyone on the stage was a poor reflection of the party, it was Gabbard herself.
"I think it's unfortunate that we have someone on the stage that is attempting to be the Democratic nominee for president of the United States who during the Obama administration spent four years full time on Fox News criticizing President Obama," Harris said, referring to Gabbard.
Gabbard responded that it was "unfortunate" Harris would "traffic in lies and smear and innuendos because she cannot challenge the substances of the argument that I am making."
"It only makes me guess that she will, as president, continue the status quo," she commented.
Carter and Earhardt agreed that the attack did not "resonate" with voters.
"It seemed personal," she noted. "It's what it felt like and it didn't do anything for Kamala Harris."
"She did not have the best night," Carter concluded.