Republican U.S. Senate candidate Manny Sethi, left, shakes hands with Republican Sen. Rand Paul of Kentucky, who has endorsed him, during a campaign event last month in Lascassas, Tenn. (AP Photo/Jonathan Mattise)

When President Donald Trump declared he would support his ambassador to Japan in the Republican primary for the open U.S. Senate seat in Tennessee a year ago last month, Bill Hagerty hadn't even announced his candidacy.

Popular former Gov. Bill Haslam hadn't said whether he would make the race.

But Nashville trauma surgeon Dr. Manny Sethi had declared his intention to run more than a month before.

Trump, at the time, was golden in Tennessee, the economy was roaring, Black Lives Matter was a discredited organization derided by Democrats and Republicans, and no one had ever heard of COVID-19.

A lot can happen in a year.

With Trump behind him — seemingly a first endorsement for a Tennessee Senate candidate from a sitting Republican president in the era in which the GOP has been ascendant in the state — and Haslam eventually turning down a run, Hagerty looked like a cinch winner.

And just in case, he wrapped himself around the president in advertising from day one of his campaign.

However, Sethi refused to go away quietly, charmed people with his warmth and declared he was the conservative outsider in the race.

He's probably still the underdog in the race, but "underdog" and "conservative outsider" appealed to Tennessee voters in 2018. That year, they eschewed the titans in the GOP primary race, U.S. Rep. Diane Black and former Haslam adviser Randy Boyd, and picked Bill Lee to be their nominee.

While Black and Boyd were bashing each other with negative television advertising, the Franklin businessman met people at town hall gatherings, listened to what they wanted from the next governor, and managed to thread the needle between the two. He then went on to defeat former Nashville Mayor Karl Dean in the general election.

Sethi doesn't have two main contenders to squeeze between, but he has run a campaign similar to Lee's. He has, that is, with the exception of Lee's refusal to use negative advertising. But with Hagerty his only real opponent, he had little choice but to answer hits against him.

Now, according to Politico, the battle between the two has become the "nastiest Republican primary in the country."

We won't recount the charges and counter charges from both sides, but they come down to little more than one attempting to taint the other with his previous verbal, organizational or monetary support for another candidate or another position on a particular issue.

The campaign's negative turn some weeks ago means one thing, though. The race is a lot closer than the Hagerty people ever thought it would be. A campaign doesn't mount negative advertising if it has no reason to worry about the result.

But we think there's something else — an intangible — at play. Tennesseans, especially in recent years, don't like to be told for whom to vote or to believe that their vote is taken for granted.

The 2018 governor's race is one example. While the experts were preparing the seat for Black or Boyd, the voters said, "Just a minute."

In 2014, voters across the country were — because of the excesses of the Obama administration — about to return the Senate to Republican control. Tennessee already had a senator, Lamar Alexander, seeking election, and he by all rights had prepared well for re-election.

But he apparently wasn't conservative enough for some Volunteer State voters, and they picked state Rep. Joe Carr — who had been running for a congressional seat — to challenge him. Alexander, the former governor and already a two-term senator, won the primary but with only 49.7% of the vote.

It was the lowest winning percentage and lowest margin of victory (9.2 points) ever in a primary for a Republican U.S. senator from Tennessee, and Carr's 40.5% of the vote was a larger percentage of the vote than the previous 11 challengers to sitting Republican senators in Tennessee history.

It was the opposite when Alexander ran for his first Senate term in 2002. In assessing the race, Vanderbilt political science professors noted how state Republicans were preferring more conservative candidates.

"The base of the Republican Party in Tennessee is becoming more conservative," said Geoff Layman, associate professor or political science, "and that hasn't always been the case in Tennessee where the Republican Party has been more moderate."

However, they said, voters chose Alexander in the primary over the more conservative, four-term congressman Ed Bryant, who was able to successfully define the race on his own terms of which candidate would be more conservative.

Will 2020 be another year in which Volunteer State GOP voters buck the conventional wisdom? We have endorsed Sethi, believing another conservative outsider will be better for the state.