He came out in support of Justice Brett M. Kavanaugh — after the searing Senate hearings. He has aired a commercial in which he shoots sporting clays and trumpets his “support of the Second Amendment” as well as his N.R.A. A rating as governor. He casually scorns his party’s drift left and leaders like Chuck Schumer in language more often heard from Republicans.

“I remember sitting down here as governor during the time of the Great Recession, where, I mean, there’s just a lot of pain, and everybody wants to talk about what bathroom somebody’s using or something, you know?” he said in an interview, when asked why this state had turned right. President Barack Obama, he added, was “a very smart guy, but kind of elitist in his leanings.”

This style helped Mr. Bredesen win the governorship twice in the previous decade, convincing him that he could capture the seat currently occupied by his close friend Senator Bob Corker, the Republican who retired rather than bite his tongue about Mr. Trump.

Yet in the immediate aftermath of the Kavanaugh confirmation fight, Mr. Bredesen saw his polling sag as conservative-leaning voters aligned themselves with the Republicans. The race has tightened again, according to public and private surveys, but the court battle was a boon to Republicans here.

Ms. Blackburn, a hard-line conservative from exurban Nashville, has delighted in the opportunity to nationalize the race: At a debate earlier this month she referred to Hillary Clinton over 20 times.

Tennessee has shifted drastically to the right in the last decade. Its congressional delegation and state legislature have become dominated by Republicans with Democrats all but extinct outside Tennessee’s major cities.