New York (CNN) Attempts to undermine Sen. Kamala Harris' racial identity had been festering on conspiratorial corners of the internet for months before being elevated to the mainstream by Donald Trump Jr. during last week's debate, an expert that tracks online misinformation tells CNN.

In addition to efforts to undermine Harris' identity as a black woman, a false claim that Harris is not eligible to run for president because both of her parents are foreign-born has also been circulating. The claim has echoes of the false birther conspiracy that was spread about President Barack Obama -- and some of the same people involved in spreading that conspiracy are involved in circulating the false claims about Harris.

Soon after Harris' debate-defining moment when she recounted being bused to school as a little girl , a swarm of Twitter accounts, many anonymous, began spreading disinformation about the senator's race.

"You. Are. Not. Black," one Twitter user, who was suspended from the service the following morning, tweeted at Harris soon after the California senator confronted former vice president Joe Biden about his comments on working with segregationist senators and his past opposition to busing.

Trump Jr. amplified those attacks when, on Thursday, he shared a tweet sent by one user with the assertion, "Kamala Harris is *not* an American Black. She is half Indian and half Jamaican."

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