Tuberville and Sessions are facing off in a March 31 race to run against Democratic Sen. Doug Jones in the fall.

Trump was long expected by Republicans in Washington and Alabama to endorse Sessions' opponent in the runoff given his vocal disdain for his former attorney general. Sessions, citing ethics guidelines and advice from Justice Department officials, recused himself from investigations into the 2016 presidential election, given his work with Trump's campaign over the course of the race.

Tuberville's finish in the top spot of the primary put him in strong position heading into the runoff, and a series of polls Tuesday showed Tuberville either leading or tied with Sessions. A poll from the independent firm Cygnal showed Tuberville ahead by 12 percentage points.

Sessions campaign released an internal poll showing the race tied at 45 percent apiece; Tuberville's campaign countered with an internal poll showing the former football coach ahead by double digits.

Sessions attempted to blunt the impact of his falling out with Trump during the primary, reminding voters constantly of his early endorsement of Trump during the presidential campaign and his support for Trump's agenda. In his final TV ad before the primary, Sessions said the other candidates "talk big about Trump, hoping to get your vote. But talk is cheap."

But the ads did not do much to blunt Tuberville's pole position in the race. And Tuberville wasted little time taking advantage of Trump's past attacks on Sessions during the runoff.

In the first TV ad after Tuesday's primary, Tuberville went after Sessions over Trump. His campaign launched an ad featuring a clip from an interview in which NBC News' Chuck Todd asked Trump what his one do-over as president would be. "I would not have appointed Jeff Sessions to be attorney general," Trump responded.

Tuberville responded to Trump's tweet Tuesday: "Looking forward to helping you drain the swamp and #KAG!" using the hashtag for the president's slogan, "Keep America Great."

