An India-born GOP Senate candidate hoping to unseat Sen. Elizabeth Warren, D-Mass., is reportedly fighting an order to take down his election sign declaring “only a real Indian can defeat a fake Indian."

Shiva Ayyadurai, who has focused his bid around Warren's claim to Native-American ancestry, filed a federal lawsuit Sunday accusing Cambridge, Massachusetts — Warren's home — of free-speech violations, The Washington Times reported.

"This is a political vendetta by City officials who are supporters of Elizabeth Warren," said India-born Ayyadurai, the outlet reported.

City officials determined the GOP candidate's signs — posted on either side of a school bus parked about a mile from Warren's house — lacked permits and approvals, The Washington Times reported. They went up March 17.

"We will not remove the slogan from our bus," Ayyadurai said, The Washington Times reported. "We will defend the First Amendment, and we will fight this egregious attack on the First Amendment, at any cost."

"They didn't say anything when we had the first sign," he added. "It was only when we put, 'Only a real Indian can defeat the fake Indian,' so it's clearly trying to censor speech."