Donald Trump mocked ex-Attorney General Jeff Sessions after it was reported his senatorial bid in the Alabama Republican primaries would be heading into a runoff election, while seemingly issuing a warning to his former appointees.

The president wrote in a tweet posted on Wednesday morning: "This is what happens to someone who loyally gets appointed Attorney General of the United States [and] then doesn’t have the wisdom or courage to stare down [and] end the phony Russia Witch Hunt."

"Recuses himself on FIRST DAY in office," he added, "and the Mueller Scam begins!"

The tweet also included a Politico article showing the results of the Alabama primaries on Super Tuesday. Mr Sessions has launched a bid to reclaim his Senate seat in the state after recusing himself from former Special Counsel Robert Mueller’s investigation into Russian interference in the 2016 election as attorney general and being forced out of his role in the Justice Department in 2018.

The bad blood between the president and the nation’s former top law enforcement officer seemed as thick as ever on Wednesday morning, despite Mr Sessions celebrating his association to Mr Trump along the campaign trail in Alabama and in a series of television ads promoting his candidacy. Mr Trump has long derided Mr Sessions for recusing himself from the federal probe, however, appointing a loyalist to the position shortly after.

Mr Sessions, 73, won 31.1 percent of the vote with nearly 97 percent of precincts reporting by Wednesday morning. He now faces a runoff election with Tommy Tuberville, a 65-year-old former college football coach, who won 32.2 percent of the vote. Bradley Byrne, a third Republican candidate, picked up 26.8 percent of the vote. Doug Jones, the Democratic incumbent senator, ran unopposed in his party’s senatorial primaries.

In his resignation letter to the president, Mr Sessions said he “aggressively advanced the policy agenda” of the White House administration. The former attorney general echoed that messaging throughout his senatorial bid, as the other Republicans in the race expressed strong support for Mr Trump.

Mr Trump won the solid-red state handedly in 2016 with 62.1 percent of the vote, and has at times enjoyed an approval rating in Alabama that’s higher than anywhere else in the country.

The president declined to endorse his former appointee during the campaign, which may have propelled Mr Sessions to the head of the pack, though he stopped short of attacking his ex-attorney general along the campaign trail.

Mr Trump told reporters he “saw [Mr Sessions] said very nice things about me last night” during a Fox News interview in which the former attorney general praised the president.

“I haven’t gotten involved,” he said about the GOP primary race in Alabama. “I haven’t made a determination.”