Former Attorney General Jeff Sessions is expected to announce plans to enter the 2020 race for the Alabama Senate seat he held before joining the Trump administration, sources familiar with the effort tell Fox News.

The sources said the announcement is likely to happen Thursday. Sessions is scheduled to join Fox News' "Tucker Carlson Tonight" on Thursday night at 8 p.m ET to discuss the race.

Should he enter the contest, he would join a crowded field of Republicans already running to take on Democratic incumbent Sen. Doug Jones. The filing deadline closes Friday afternoon.

Sessions has not spoken with President Trump or Majority Leader Mitch McConnell about running for his old Senate seat, the sources said. He has hired Curt Anderson of On Message to be his campaign consultant.

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Sessions, who resigned from the Justice Department a year ago Thursday amid public attacks from the president he served, was one of Trump’s most loyal and trusted advisers before their relationship soured over his recusal from the Russia investigation.

A major question hanging over Sessions’ entrance into the race is whether Trump -- who remains popular in Alabama -- will take steps to thwart his bid. Trump is scheduled to visit Alabama this weekend to attend the Alabama-LSU game college football game on Saturday.

Other Republicans running include U.S. Rep. Bradley Byrne, former Auburn football coach Tommy Tuberville, former Alabama Supreme Court chief justice Roy Moore, Alabama Secretary of State John Merrill, businessman Stanley Adair and state Rep. Arnold Mooney.

After Sessions resigned from the Senate to become attorney general, Jones in 2017 pulled off a major upset in Alabama by defeating Moore, becoming the first Democrat to win election to the Senate from the deeply conservative state in 25 years.

Moore had faced multiple allegations he pursued romantic relationships with teenage girls while he was in his thirties – accusations he denied. He is seeking the Republican nomination again for the seat in 2020.

Prior to Sessions’ resignation last year, Trump repeatedly lambasted Sessions over his recusal, saying he wouldn’t have installed him as the country’s top law enforcement officer had he known his attorney general would recuse himself from the Russia probe.

Trump’s falling out with Sessions was remarkable, considering the pivotal and trusted role the Alabama Republican played for Trump during the campaign.

Sessions -- who bonded with Trump over their populist views on trade and immigration -- became the first sitting senator to endorse Trump in February 2016 when he announced his support of the New York businessman’s then-underdog campaign.

Sessions went on to become one of Trump’s most outspoken and prominent surrogates during the campaign. A number of Sessions’ top staffers – including Rick Dearborn and Stephen Miller – took senior White House roles. When other Republicans abandoned Trump after the release of the “Access Hollywood” tape just days before the general election, Sessions stood by Trump.

After Trump won the White House, Sessions, who faced no opposition in his 2014 re-election to the Senate, gave up a safe seat to become Trump’s attorney general.

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During his confirmation hearing, Sessions denied accusations from Democrats that he had made racially insensitive statements in the past. Though most Democrats voted against their former colleague, his confirmation was seen as redemption for Sessions, whose nomination for a 1986 federal judgeship was rejected by the Senate Judiciary Committee at the time.

As attorney general, Sessions cracked down on illegal immigration, vowing to enforce federal law.

Fox News' Mark Meredith contributed to this report.