A Cherokee Nation citizen who has been critical of Sen. Elizabeth Warren's (D., Mass.) claims of Native American heritage said he was disrespected by the senator's presidential campaign.

Joseph Pierce, an associate professor at Stony Brook University in New York, tweeted Saturday that a Warren team member had tried to convince him to vote for Warren during a campaign drive earlier that day. Pierce said the Massachusetts senator had not done enough to "right the harm she has caused," referring to the decades of claims of Cherokee heritage for which Warren apologized only this year.

The Warren staffer took Pierce to another team member, who, Pierce wrote, promised to make "real time" for him. Pierce said the staffer was dismissive when Pierce said he was "pissed" about Warren's claims.

"I mean, bro, just one second earlier you were willing to ‘make real time for me,' and when you saw that I actually have thoughts about this, you no longer have that willingness or that time. That, my friend, is exactly the problem," Pierce tweeted.

According to Pierce, the staffer also told him that not voting for Warren would help President Donald Trump win reelection. Pierce called that posture "profoundly colonial."

So, irony of ironies: There was an @ewarren campaign, recruitment thing on my block today, and when I walked outside, a guy tried to convince me to vote for her. I said, "I'm Cherokee and she hasn't done enough to right the harm she has caused." AND THEN… — Joseph M. Pierce (@PepePierce) October 5, 2019

the guy said that he would take me to someone "who could get the word to Elizabeth." Intrigued, I go with him, and its a white guy with a beard, and we interrupt his conversation, because its important, and I say, "I'm Cherokee" and he nods… — Joseph M. Pierce (@PepePierce) October 5, 2019

He says that he wants to "make real time for me" and if he can have my number so we can talk later. I say, "this really pisses me off". And then things change: he can see that I'm upset, and then tries to figure out if I am worth talking to after all. — Joseph M. Pierce (@PepePierce) October 5, 2019

He says, "I'm not sure there is anything I can do for you". And it dawns on me, yes, I am upset, perhaps I'm not willing to have this conversation, perhaps I just want to yell. So I say, "tell her, tell someone, that what she has done is not enough." — Joseph M. Pierce (@PepePierce) October 5, 2019

He says, "I'm not sure there is anything I can do for you". And it dawns on me, yes, I am upset, perhaps I'm not willing to have this conversation, perhaps I just want to yell. So I say, "tell her, tell someone, that what she has done is not enough." — Joseph M. Pierce (@PepePierce) October 5, 2019

I mean, bro, just one second earlier you were willing to "make real time for me," and when you saw that I actually have thoughts about this, you no longer have that willingness or that time. That, my friend, is exactly the problem. — Joseph M. Pierce (@PepePierce) October 5, 2019

And he had the gall to say that if I didn’t vote for her it was going to get Trump re-elected. This is the position they are putting us in, and it is profoundly colonial. Profoundly. — Joseph M. Pierce (@PepePierce) October 6, 2019

Pierce told the Washington Free Beacon he had nothing to add when reached about his story. The Warren campaign did not respond to a request for comment.

The anecdote underscores how Warren, who has risen in the polls to become one of the frontrunners in the 2020 Democratic primary fight, still faces lingering problems with her past claims.

In August, Warren apologized at a Native American candidates' forum for her "mistakes," while not specifying what they were.

"Like anyone who's being honest with themselves, I know that I have made mistakes," she said. "I am sorry for harm I have caused. I have listened and I have learned a lot, and I am grateful for the many conversations that we've had together. It is a great honor to be able to partner with Indian Country, and that's what I've tried to do as a senator, and that's what I promise I will do as president of the United States of America."

Pierce attended the forum and penned an op-ed in which he called Warren's apology inadequate and criticized her "dangerous claims that undermine Cherokee sovereignty." While he praised her plan for aiding Indian Country, he wrote that Warren had not done enough to win back its trust.

"If Warren is truly invested in repairing the harm that she has caused, then she needs to sit down with Cherokee people, rather than putting the discussion off for another day," Pierce wrote. "She needs to start building an ethical relationship with the Cherokee Nation by admitting precisely what she has done, explaining why it was wrong, and doing more than proposing a ‘plan' to fix it. This requires action. Short of that, she is not demonstrating that she has the willingness or the capacity to make this right."

Throughout Warren's academic and political career, she claimed to have Native American ancestry, with nothing but family lore supporting her claims. Trump mocked Warren for her claims, calling her "Pocahontas," which in turn led Warren to release a poorly received DNA test showing she was as little as 1/1,024th Native American.

The Washington Post later reported that she listed her race as "American Indian" on a 1986 State Bar of Texas registration card, leading to a fresh round of apologies from Warren just as she was officially launching her 2020 presidential campaign.