The president will hold a fundraiser and campaign-style rally in Nashville to boost GOP Rep. Marsha Blackburn and attempt to knock down Democratic former Gov. Phil Bredesen. They are vying for the Senate seat currently held by Republican Sen. Bob Corker, who declined to run for a third term.
Making things more complicated, Corker hasn't given a full-throated endorsement to Blackburn, and he has said he considers himself a friend of Bredesen's.
Polls have shown a close contest between Blackburn, a longtime member of Congress who has run as a staunch Trump supporter, and Bredesen, a two-term governor who last won a statewide election in 2006. Bredesen hopes to win a seat in a state that last had a Democratic senator in the mid-1990s.
The Tennessee race holds major stakes for Republicans' push to keep or expand their 51 to 49 seat majority in the Senate. Winning Corker's seat could help Democrats cancel out other possible losses in 2018 Senate elections, as the party tries to defend 10 seats in states Trump won in 2016.
Trump has already gotten himself involved in several of those races. He has made trips in part to damage Democratic senators such as Joe Donnelly of Indiana and Joe Manchin of West Virginia. He has repeatedly slammed red-state Senate Democrats for not supporting his agenda.
Democrats have targeted a handful of GOP-held seats, most notably in Nevada and Arizona. Corker's departure also gave the party a bigger opening in Tennessee, where the race appears closer than many Republicans would hope.
A Mason-Dixon Polling survey last month found a 3-percentage-point edge for Bredesen, an advantage within the poll's margin of error. A separate Middle Tennessee State University poll taken in March showed a 10-percentage-point edge for Bredesen.
A Vanderbilt University poll earlier this month found Bredesen had a 67 percent favorability rating among Tennessee voters, versus 49 percent for Blackburn. He also had a 69 percent to 44 percent edge among independents.
Blackburn has largely pegged her hopes in the race to Trump's popularity in Tennessee. She has promised to promote Trump's policy agenda in the Senate, a chamber where GOP lawmakers have proven more likely to call out the president than in the House. Blackburn has voted with Trump's position 92 percent of the time, according to FiveThirtyEight.
A video released by Blackburn's campaign Monday said, "President Trump will be much more successful if we had people up there that are going to get things accomplished." It featured a clip of Trump thanking the congresswoman for her role in pushing for rural broadband access.
Blackburn's push to tie herself closely to Trump may partly be a reaction to Corker. The senator has criticized the president several times, at one point saying Trump's behavior could put the U.S. "on the path to World War III."
Corker has notably hesitated to take sides in the Senate race, prompting questions about whether he could lead other Republicans to shy away from Blackburn. Last month, the senator said he would not campaign against Bredesen, whom he called a "friend."
Corker said he had a stronger working relationship with Bredesen than with Blackburn. The senator was the mayor of Chattanooga when Bredesen was governor.
Still, Corker said he is "supportive" of Blackburn and donated to her campaign.
Bredesen, like some other Democrats running in key red state elections, has avoided criticizing Trump.
"I don't want to come across as somebody who is the toy of the national Democratic Party," Bredesen told CNN in late April.
Bredesen has long touted his effort to work with Republicans and said in a campaign ad in March that he is "not running against Donald Trump." As Trump heads to Tennessee on Tuesday, Bredesen plans to spend the day at a manufacturing facility in the eastern part of the state.
While he trails Blackburn heavily in fundraising, Bredesen last month got some help from former Vice President Joe Biden, whom Democrats hope can appeal to centrist donors and voters in various swing races this year.
Considering Blackburn's rhetoric and Trump's involvement in the race, Tennessee voters' views of the president may prove critical. The Vanderbilt survey found the president had a 53 percent approval rating in the state, up 5 points since December.
Still, Trump's own comments about the 2018 elections have raised questions about how much he can motivate Republicans. Last week, he questioned how important this year's midterms really are.
"Your vote in 2018 is every bit as important as your vote in 2016," he said at an event hosted by the Susan B. Anthony List. "Although I'm not sure I really believe that, but you know. I don't know who the hell wrote that line."