A Republican candidate who is running against Sen. Elizabeth Warren (D-MA) for the Senate is challenging Warren’s unfounded claim that she is of Native American ancestry.

GOP U.S. Senate candidate V.A. Shiva Ayyadurai sent Warren a fully paid DNA test kit from 23&Me through Amazon last week to see if she is willing to back up her claims of Native American heritage.

Celebrate @SenWarren's Birthday.DONATE $5 to https://t.co/1PTolkbkSF to support REAL INDIAN vs. FAKE INDIAN DNA Test. My gift: HER DNA kit! pic.twitter.com/NDsxVEBX5n — Dr. Shiva Ayyadurai,PhD (M.I.T.) Inventor of Email (@va_shiva) June 22, 2017

When Warren did not accept Ayyadurai’s gift, Ayyadurai posted a receipt on Twitter of his refunded purchase and wrote that he was “deeply saddened” the progressive Massachusetts senator did not accept his “thoughtful birthday gift.”

I'm deeply saddened @SenWarren refused my thoughtful (gift-wrapped) Birthday Gift: the 23&me DNA Test Kit. Most unfortunate! #FakeIndian pic.twitter.com/BI7F20wDW8 — Dr. Shiva Ayyadurai,PhD (M.I.T.) Inventor of Email (@va_shiva) July 2, 2017

Ayyadurai has made it a point in his campaign to challenge Warren’s claims of Native American ancestry, which no documentation has been able to prove.

Instead, Warren pointed to a “family newsletter” from 2006 stating that her 3rd great-grandmother was a Cherokee Indian as proof of her heritage uncovered by an amateur genealogist.

Warren’s campaign also claimed that the Massachusetts senator is Native American because her cousin Candy Rowsey edited a cookbook called Pow Wow Chow. A Boston talk radio show host found in 2012 that Warren plagiarized two recipes that she submitted to the cookbook.

Ayyadurai, meanwhile, is using the lack of documented evidence of Warren’s heritage to his advantage. He coined the campaign slogan, “Only a real Indian can defeat the fake Indian” in a direct attack on Warren’s unfounded claims.

https://twitter.com/va_shiva/status/878250159968108544