WASHINGTON (Reuters) - U.S. Attorney General Jeff Sessions on Thursday defended his decision not to appoint a second special prosecutor to investigate Republicans’ concerns about the FBI by noting that Special Counsel Robert Mueller’s Russia probe had already taken on “a life of its own.”

U.S. Attorney General Jeff Sessions testifies before a Senate Appropriations Commerce, Justice, Science, and Related Agencies Subcommittee hearing on the proposed budget estimates for the Justice Department, on Capitol Hill in Washington, U.S., April 25, 2018. REUTERS/Yuri Gripas

Speaking to a U.S. House appropriations panel during a routine budget hearing, Sessions told lawmakers that the Justice Department needed to “be disciplined and stay within our classical procedure and rules” before rushing to hire more special counsels.

“I do not think we need to willy-nilly appoint special counsels,” he said, after listening to a laundry list of frustrations aired by West Virginia Republican Congressman Evan Jenkins.

“As we can see, it can really take on a life of its own.”

Sessions has often found himself in the crosshairs of President Donald Trump’s wrath because of his decision to recuse himself from overseeing the probe into whether Trump’s presidential campaign colluded with Russia.

Trump has repeatedly denied any collusion with Russia, has called the probe a “witch hunt,” lamented tapping Sessions as attorney general, and mused about whether to fire Mueller or Deputy Attorney General Rod Rosenstein, who oversees the probe due to Sessions’ recusal.

Trump’s ire was further provoked more recently after the FBI raided the office and home of his personal attorney, Michael Cohen.

In an interview on “Fox and Friends” early Thursday, Trump hinted he might get more aggressive in trying to shake up leadership at the Justice Department, saying: “I’ve taken the position - and I don’t have to take this position and maybe I’ll change - that I will not be involved with the Justice Department.”

Republicans frustrated by the Mueller probe have since launched investigations into other matters such as the FBI’s handling of the Hillary Clinton email investigation and whether the Justice Department committed abuses when it applied to a special court for a warrant to conduct surveillance on Carter Page, a former Trump national security campaign adviser.

In response to those concerns, Sessions asked U.S. Attorney John Huber of the District of Utah to independently review the issues, rather than hiring a special prosecutor.

On Thursday, Sessions staunchly defended the FBI, calling its director, Christopher Wray a “man of integrity,” and warned lawmakers not to “smear everybody” at the department.

Jenkins urged Sessions to reconsider on tapping a second special counsel, noting his constituents are losing patience.

“We are frustrated we have had a special counsel... investigating collusion over a year without a scintilla of evidence,” he said.

Sessions responded that he understands why some Americans - and Trump - may be frustrated.

“I think the American people are concerned and the president is concerned,” Sessions said.

“He is dealing with France and North Korea and Syria and taxes and regulations and border and crime every day.”

“This thing, he continued, “needs to conclude.”