President Trump listens as Attorney General Jeff Sessions speaks during a swearing-in ceremony at the White House on Feb. 9, 2017. (Jabin Botsford/The Washington Post)

President Trump is “not on board” with his former attorney general, Jeff Sessions, running for the Senate, Sen. Richard C. Shelby (R-Ala.) told the Hill on Thursday.

The Alabama Senate seat is considered a prime pickup opportunity for Republicans, and Sessions’s name has been in the mix as a potential candidate who could win it.

Shelby said Sessions would be a strong candidate for a seat he held before joining the Trump administration, but could “struggle if the president was against him.” In conversations with Trump about the race, Shelby said Trump “was not encouraging” of Sessions running.

“How do I say it? He was not on board, okay?” Shelby said.

Trump fired Sessions in November after a tumultuous relationship that began when Sessions recused himself from the Russia investigation. In July 2017, Trump expressed his displeasure, saying Sessions “should have told me before he took the job and I would have picked somebody else.”

Trump continued to air his grievances with Sessions on Twitter and in interviews until finally forcing him out. Trump didn’t stop deriding Sessions even after he was gone. At the annual Conservative Political Action Conference in March, Trump brought up Sessions.

“I’m gonna recuse myself,” Trump said in an accent mimicking Sessions’s Southern drawl.

Sessions, who was one of the first Republican members of Congress to endorse Trump, gave up his Senate seat to run Trump’s Justice Department. The seat was then won in a special election by Doug Jones (D) after the GOP candidate, Roy Moore, was accused of kissing and propositioning underage girls.

Moore is seeking a rematch with Jones, but national Republicans aren’t supporting him, worried that he’ll lose again. Even Trump, who rallied for Moore in Alabama after the allegations of sexual misconduct came out, has urged him not to run.