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Mississippi Sen. Cindy Hyde-Smith, who faces a runoff this month, said on Monday her campaign has returned a $2,700 donation from a Seattle businessman who was sued for discriminating against Muslims in his hiring practices.

Campaign finance records show that Peter Zieve, who owns aerospace supplier Electroimpact, donated $2,700 to Hyde-Smith's campaign on Nov. 14.

Melissa Scallan, a spokeswoman for Hyde-Smith's campaign, told NBC News that the campaign has since returned the donation.

"That donation was made online, and we have returned it," she said in a statement.

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Zieve was sued in 2017 by the state of Washington for refusing to hire Muslims at his company and expressed "hatred" for Muslims at work, according to court records. He also offered $1,000 "marriage bonuses" and "child bonuses" to employees to encourage them to procreate, according to the lawsuit, writing in an email revealed in court documents that he wanted to prevent the U.S. from becoming "backfilled with rubbish from the desperate and criminal populations of the Third World." He was also accused of requiring applicants to submit photos of themselves before applying for engineering jobs at his company, records show.

In 2017, a year-long investigation by the Washington state attorney general found Zieve's company broke state law by discriminating on the basis of religion and marital status. Zieve then entered into a 42-month, court-monitored consent decree with the attorney general's office that required the Mukilteo-based company to pay $485,000 settlement and removed him from making direct hiring decisions.

In the consent decree, Electroimpact denied it did anything wrong.

Zieve donated to Hyde-Smith's campaign on Nov. 14, days after a video in which she says she would be "on the front row" if a supporter invited her to "a public hanging" went viral, but denied that her remark prompted his donation, according to The Jackson Free Press.

Zieve told The Jackson Free Press on Friday that he donated to the incumbent lawmaker's campaign because he believes "she’s a Republican." Asked about her remarks, he said, "I don't know anything about that. Sorry, I can’t help you. Bye."

Hyde-Smith faces a runoff election Nov. 27 against former Secretary of Agriculture Mike Espy, who is African-American. Her "public hanging" comments drew sharp rebuke from both sides, with many linking it to Mississippi's brutal history of racial violence and lynching against African Americans, though Hyde-Smith insisted there was no negative connotation.

Zieve, who did not respond to a request for comment from NBC News, has donated to several Republican candidates this year, according to campaign finance records. He also contributed to President Donald Trump's 2016 presidential campaign.