In the first television ad bought in Tennessee's 2020 U.S. Senate race, Republican candidate Manny Sethi is focusing on illegal immigration — and his own ethnicity.

Sethi, a Nashville trauma surgeon in his first bid for office, is up against Bill Hagerty, the former U.S. ambassador to Japan.

Both men are attempting to prove their conservative bona fides, a tactic that proved successful for U.S. Sen. Marsha Blackburn, who defeated moderate Democratic former Gov. Phil Bredesen in last year's closely watched Senate race.

"Let ‘em try to call me a racist," Sethi says in the ad, which features his mother, Dr. Chandler Sethi, sharing the story of how she and her husband fulfilled all legal requirements to immigrate to the United States as young doctors from India.

"We’re gonna have an illegal immigrant invasion if Republicans don’t win in 2020," Sethi said.

The ad, released on Tuesday, will immediately begin airing across Tennessee and in Washington, D.C. The campaign has not said how much it is spending on the ad, which

Sethi, taking a page from Gov. Bill Lee's campaign, has attempted to portray himself as a conservative outsider in the race against Hagerty.

Chris Devaney, who served as Lee's campaign manager, resigned this summer from the new governor's administration to work as campaign chairman for Sethi.

Hagerty received an endorsement from President Donald Trump — whose presidential transition he helped oversee — but entered the Senate race only after former Gov. Bill Haslam, a moderate Republican, decided he would not be running for the seat.

Reach Natalie Allison at nallison@tennessean.com. Follow her on Twitter at @natalie_allison.

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