It is unclear whether Trump's presence in the race would help or hurt Blackburn during an election year in which many voters have pushed back against Trump and GOP policies. Fifty percent of Tennessee adults said they approve of Trump, while 44 percent said they disapprove, according to Gallup survey results published in January.
Blackburn, who has run as a pro-Trump candidate, thanked Trump in a statement for "both his support and leadership."
"Tennesseans from all walks of life support the President's work to cut taxes, rebuild the military, care for our veterans, and nominate conservative judges who won't legislate from the bench," she said in a statement. "They expect Tennessee's next Senator to work alongside the President and their Senate colleagues to pass his agenda, and I'm looking forward to doing exactly that."
Bredesen, who served two terms as Tennessee's governor, faces a challenge to win in a state Trump carried with more than 60 percent of the vote in 2016. However, comments from Corker this week and a recent poll suggest the race may be more competitive than Republicans would hope.
On Wednesday, Corker told reporters he thinks Bredesen has a "real" 6-percentage-point advantage in the race. Polling has been scarce so far, but one Middle Tennessee State University survey in late March showed a 10-point edge for Bredesen.
Corker called Bredesen a "friend" with whom he has worked for more than 20 years. The senator said Wednesday he does not plan to attack the former governor.
"I'm not going to campaign against someone who I've been a friend with and worked with, you know? So that's the way it's going to be," Corker said at a Christian Science Monitor breakfast.
Corker has shown some support for Blackburn, who has served in Congress since 2003. On Wednesday, he said he gave her campaign an undisclosed contribution. He added that he is "supportive."
However, he said he had a stronger working relationship with Bredesen than he did with Blackburn.