Advisers to Sen. Kamala Harris, D-Calif., believe that her plunge in the polls over the summer was accelerated by a withering attack in a primary debate in July by Rep. Tulsi Gabbard, D-Hawaii, that left the then-front-runner reeling and donors “alarmed,” according to a new report about her struggling presidential bid.

In a lengthy deep-dive into the California senator’s struggles on the campaign trail, The New York Times on Friday reported that many Harris advisers point to a July debate moment between Gabbard and the senator as “accelerating” her decline in the polls.

TULSI GABBARD RIPS KAMALA HARRIS ON HER RECORD AS CALIFORNIA PROSECUTOR DURING SECOND DEBATE

In that debate in Detroit, Mich., Gabbard took aim at Harris’ record as a prosecutor, saying she was “deeply concerned” about it.

"There are too many examples to cite but she put over 1,500 people in jail for marijuana violations and then laughed about it when she was asked if she ever smoked marijuana," Gabbard said.

She also blasted Harris for maintaining the cash bail system which, she argued, disproportionately hurt poor people. Gabbard accused Harris of keeping prisoners beyond their sentence in order to use them as "cheap labor" as well as blocking evidence that would have "freed an innocent man from death row."

"The bottom line is, Senator Harris, when you were in a position to make a difference and impact in these people's lives, you did not," Gabbard responded.

It was the latest in a series of attacks from Gabbard — and Harris' advisers were reportedly unimpressed, especially as she had been prepped on potential attacks on her record. Harris responded then claiming that she had consistently fought against the death penalty and reformed the criminal justice system.

GABBARD ACCUSES HARRIS OF 'LIES AND SMEARS' IN FIERY DEBATE CLASH

According to the Times, several of Harris’ donors were “alarmed” and urged the campaign to fire back at Gabbard. Harris was also aware that her response was “insufficient,” a view “reinforced by her advisers” according to the Times.

Harris' advisers were also frustrated at the senator’s alleged inability to “carry a message beyond the initial script.”

According to the RealClearPolitics average of polls for the nomination, Harris was in second place in early July, commanding an average of 15 percent of primary voters. But since then, she has declined quickly.

Now, RCP polls have her with an average of just under 4 percent — far behind candidates such as former Vice President Joe Biden (27 percent), Sen. Bernie Sanders, I-Vt. (18.3 percent), Sen. Elizabeth Warren, D-Mass. (15.8 percent), and South Bend Mayor Pete Buttigieg (11 percent).

Harris attemped to hit back at Gabbard this month, accusing her on spending “the course of this campaign criticizing the Democratic Party.”

“What we need in November is someone on this stage who has the ability to win, someone who has the ability to go toe to toe with Donald Trump, and someone who has the ability to rebuild the Obama coalition and bring the country back together,” Harris said.

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But Gabbard hit back.

“What Senator Harris is doing, is, unfortunately, continuing to traffic in lies and smears and innuendos because she cannot challenge the substance of the argument that I’m making,” she said.

Fox News’ Sam Dorman and Brooke Singman contributed to this report.