If a Trumpian populist created his perfect Senate candidate in a lab, the result might look something like Dr. Manny Sethi.

The 42-year-old orthopedic-trauma surgeon is a staunch opponent of illegal immigration, and he is effectively using his family’s story — his parents immigrated legally to the United States from India — to his advantage as he seeks to become Tennessee’s next Republican senator.

In one campaign ad, Sethi’s mother, also a doctor, looks directly into the camera and tells viewers the story of her long process of immigrating to America, where she worked hard and delivered thousands of Tennessee babies.

“So why do others get to break the law, get benefits, and if you dare say that’s wrong, you are called racist?” she asks, before endorsing her son, who then appears on screen. “We’re going to have an illegal-immigrant invasion if Republicans don’t win in 2020. The Democrats are going to give this country away,” he says. “Let ’em try to call me a racist.”

The 2020 Senate primary is a stark example of how the Tennessee GOP has changed in the era of Donald Trump. For many years, the state has tended to elect a certain kind of business-friendly, relatively moderate Republican to the upper chamber. In 2013, both of the state’s Republican senators, Bob Corker and Lamar Alexander, voted for the ill-fated, bipartisan “Gang of 8” immigration-reform bill. And after Trump’s win in 2016, both men developed a more complicated relationship with the president than the typical Republican in Congress: Corker was a sharp critic of Trump’s trade policy, and Alexander condemned Trump for the conduct that led to his impeachment while still voting against removing him from office.

“Tennessee has typically sent more pragmatic middle-of-the-road-type Republicans to the Senate — Lamar Alexander, Bob Corker, Bill Frist, Howard Baker,” says Jessica Taylor, a Tennessee native who analyzes Senate races for the Cook Political Report. The import of the 2020 GOP primary is that “Tennessee is poised to have two very different senators than it has.” Following Corker’s 2018 retirement, his seat was filled by the more conservative Marsha Blackburn, and the man elected to succeed the retiring Alexander in November will be much more populist, regardless of the outcome of the August 6 GOP primary.

Sethi is running as the insurgent outsider and trying to claim the mantle of Trumpism in the race. But his chief opponent, Bill Hagerty, is a businessman who served as Trump’s ambassador to Japan for two years and has the president’s formal endorsement. And both candidates have pitched themselves as hardline opponents of illegal immigration who want to end birthright citizenship for children born in the United States to illegal immigrants.

While Trump’s job approval rating is underwater nationally, he remains popular among Tennessee Republicans, and Hagerty reminds voters of the president’s endorsement every chance he gets. “I went in and gave six months of my life to help President Trump get elected,” he says of his decision to volunteer “full-time” for Trump’s general-election campaign in 2016.

Sethi has hit back by contrasting Hagerty’s support of Marco Rubio in the March 1, 2016 Tennessee GOP primary with his own avowed support of Trump. “I immediately was drawn to [Trump] because he just said the things that really no one else was willing to say but everybody was thinking them,” Sethi says. “And I voted for him in the 2016 presidential primary.”

Sethi now has the backing of Senators Ted Cruz and Rand Paul, while Hagerty has the support of Blackburn and Senators Tom Cotton and Mitch McConnell. Hagerty began the race as a heavy favorite, but polls suggest that Sethi has come from behind to make the race a toss-up. A recent poll by JMC Analytics found Hagerty leading Sethi 30 percent to 27 percent, with 32 percent of Tennessee Republicans undecided.

How will undecided voters make up their minds?

With little separating the Tennessee GOP Senate candidates on the issues, the contest between Sethi and Hagerty has focused more on their respective biographies, their associations, and their loyalty to Trump.

Hagerty says his experience as U.S. ambassador to Japan has made him keenly aware of the threat from Communist China. “I want to see us get our supply chains back from China, end our dependency on China for antibiotics, for medical supplies, for high technology,” he says.

Sethi contends that as a doctor, he would have a unique ability to speak out against Obamacare and Planned Parenthood. “As a Christian, I believe all life begins at conception. As a doctor, I’ve sworn to protect life,” Sethi says. “You can’t on the one hand support the Black Lives Matter movement and on the other hand support Planned Parenthood. It just makes no sense because Planned Parenthood puts these abortion clinics in underserved neighborhoods across the country and kills millions of African-American children — babies. And I would make that hypocrisy very clear in the U.S. Senate.”

With no significant policy differences to fight over, the campaigns have tried to make mountains out of molehills.

Hagerty has hit Sethi for associating with critics of Blackburn and Trump. Sethi has gone after Hagerty for sitting on the board of a company that used the hashtag #BlackLivesMatter in a tweet, portraying the tweet as an endorsement of the official “Marxist” Black Lives Matter organization. (Hagerty agreed and resigned from the company’s board.) And in recent days, the two have traded attacks over past donations to Democratic candidates. Sethi dismissed his $50 contribution to congressional candidate Tom Perriello in 2008 as nothing more than his family buying some t-shirts to help a “family friend’s brother-in-law running for Congress.” Hagerty deflected when asked twice for an explanation of his $1,000 donation to Al Gore in 2000, saying simply that people need to focus on Trump’s endorsement of his candidacy.

Neither candidate is doing much to appeal to the Republican primary voters who have elected more moderate Republicans to the Senate for decades, and who preferred Alexander to a populist outsider by nine percentage points in the 2014 GOP primary.

On June 30, Alexander issued a plea for Americans to wear masks when appropriate in order to limit the spread of the coronavirus and help the country return to some semblance of normalcy. He lamented that this “simple lifesaving practice has become part of a political debate that says: If you’re for Trump, you don’t wear a mask; if you’re against Trump, you do.” On July 3, Tennessee GOP governor Bill Lee allowed local authorities to issue mask mandates. But both Sethi and Hagerty are categorically opposed to such mandates, and Sethi has gone so far as to call them unconstitutional.

“If you’re in a high-density area with a lot of COVID, I think you should wear [a mask]. I’m against mandates completely because I don’t think they’re constitutional,” says Sethi. “If someone starts telling you today you’ve got to wear a mask, what are they going to tell you tomorrow you’ve got to do for public safety and health?”

“People in Tennessee certainly don’t care to have the government tell them what to do. I trust the judgment of Tennesseeans. I trust individual store owners to do what they want and need for their customers and for their employees,” says Hagerty.

Despite the surge of coronavirus cases in Tennessee — the average number of new daily cases jumped from fewer than 500 in early June to more than 2,700 in late July — both campaigns have proceeded with indoor, mask-optional campaign events.

“There has been a shift in the party,” says Vanderbilt political-science professor John Geer. Tennessee GOP politics now looks a lot more like Alabama GOP politics. In the Alabama Republican Senate primary in 2017, the Trump-endorsed Luther Strange lost to Judge Roy Moore, who successfully claimed to be the true Trumpist candidate. In the 2020 Alabama Senate primary, Trump-endorsed Tommy Tuberville beat Trump’s first attorney general, Jeff Sessions, who enraged the president by recusing himself from the Russiagate investigations. Sessions, back in private life and seeking his old seat, couldn’t withstand Trump’s withering attacks throughout the race.

“Hagerty ran a campaign that was basically Trump’s endorsement, which at one level makes you feel good when you look, for example, at what happened in Alabama [this year],” says Geer. “The difference is that Trump hasn’t attacked Sethi like he did Sessions.”

As a result, the race is “obviously a lot closer than people thought it would be,” Geer adds. “Flip a coin right now about how it all works out.”