Sessions said in the letter that hat John Huber, a USA attorney in Utah, was working in coordination with the Inspector General's office on the matters the Republicans raised in their request for a second special counsel earlier this month.
"I receive regular updates from Mr. Huber and upon the conclusion of his review, will receive his recommendations as to... whether any matters merit the appointment of a Special Counsel", Sessions said on Thursday.
Attorney General Jeff Sessions declined to appoint a special counsel to probe anti-Trump bias in the Federal Bureau of Investigation. During the Trump administration's removal of Obama holdover USA attorneys in March 2017, Huber submitted his resignation, but he was reinstated to his job via a temporary appointment by Sessions.
"To justify such an appointment, the Attorney General would need to conclude that 'the public interest would be served by removing a large degree of responsibility for the matter from the Department of Justice", Sessions wrote.
Sessions revealed in the letter that he had named US Attorney John W Huber to lead a review of issues previously raised by the lawmakers.
"Any objective review of these claims should tell us what we already know - that the FBI was right, that there was sufficient evidence to continue investigating certain Trump campaign officials for their connections to the Russian government, and that the Republicans are desperate to distract from that investigation", he added.
"Jeff Sessions' photo on the cover of TIME is creepy as hell", Sarah Lerner said on Twitter.
President Trump had demanded last month that Mr. Sessions turn to Justice Department lawyers, not the inspector general, to investigate accusations of surveillance abuse.
An FBI agent in Minnesota has been charged over leaking secret documents to The Intercept, reportedly related to threats made by individuals from a particular Middle Eastern country and the FBI's use of informants.
Nonetheless, his decision not to appoint a special counsel, at least for now, is nearly certain to disappoint Republicans. That investigation was formally announced on Wednesday.
"For instance, the IG's office does not have authority to compel witness interviews, including from past employees, so its investigation will be limited in scope in comparison to a Special Counsel investigation", Goodlatte said in a statement.
Sessions' and Boyd's letters refer to multiple "senior federal prosecutors", but Flores declined to comment on who else Huber was working with on the review.