Justice Department Inspector General Michael Horowitz has reportedly completed his investigation into alleged Foreign Intelligence Surveillance Act abuses by the Justice Department and FBI.

The Hill's John Solomon made the announcement Thursday evening on Fox News.

"What I can report tonight, Sean, is that the IG has completed his work on the FISA abuse report. It's expected to be transmitted as early as next week to Attorney General William Barr and that will begin a process of declassification," the investigative reporter told host Sean Hannity.

"I think we are still on track for that timeline, I've been saying on your show: mid-September to early October seems the most likely release point," Solomon said. "It's going to be a tough report," he added.

The timeline for Horowitz's investigation, which began in March 2018, has repeatedly shifted over the past few months because of various developments.

Horowitz's team is examining the FISA application and three renewals beginning in October 2016 to surveil former Trump campaign adviser Carter Page. The applications relied heavily on the unverified dossier compiled by British ex-spy Christopher Steele, who was hired by opposition research firm Fusion GPS and funded by Democrats.

Republicans have argued the dossier's Democratic benefactors, which included Hillary Clinton's 2016 campaign and the Democratic National Committee, and its author's anti-Trump bias were left out of the FISA applications, and they have demanded accountability. Democrats countered that the FBI acted appropriately, saying the Justice Department and the FBI met the rigor, transparency, and evidentiary basis for probable cause.

Meanwhile, Barr's "investigation into the investigators" is underway, and the attorney general has said he is working very closely with Horowitz. The inspector general can recommend prosecutions, and U.S. Attorney John Durham, whom Barr tasked to lead the review of the origins of the Russia investigation, has the ability to convene a grand jury and subpoena people outside the government.

Senate Judiciary Committee Chairman Lindsey Graham, a close Trump ally, has promised a "deep dive" into the origins of the Trump-Russia investigation after Horowitz completes his work. Over the past few days, the South Carolina Republican has said he expects Horowitz's findings to be "damning and ugly" for the DOJ. Graham also said he plans to meet with Barr this week to "talk to him about how best to tell the story" and predicted that after his report is released Horowitz will deliver "chilling testimony" in front of his panel.