Sen. Lindsey GrahamLindsey Olin GrahamBernie Sanders to Trump: Firing Mueller 'an impeachable offense' The Memo: Lawyer’s exit signals harder line by Trump Senators introduced revised version of election cyber bill MORE (R-S.C.) on Friday warned that special counsel Robert Mueller, who is directing the Justice Department's investigation into Russian election meddling, will be held responsible for any leaks from his probe.

The South Carolina Republican told Fox News that while he will "respect" the grand jury process, he will "hold Mueller accountable" for any leaks.

"If we get constant leaks coming out of the grand jury then he needs to be held accountable for that. That's not fair to the president," Graham said.

Graham's comments come after sources told The Wall Street Journal that Mueller has impaneled a grand jury located in Washington, D.C., as part of his investigation into Russian interference in the 2016 presidential election.

CNN also reported on Thursday that the investigation has branched out into possible financial crimes. Meanwhile, sources told Reuters that subpoenas relating to a mid-2016 meeting between Donald Trump Jr. and a Russian lawyer have also been issued.

"No American, including President TrumpDonald John TrumpScarborough mocks 'Deflection Don' over transgender troop ban Pelosi condemns Trump's 'cowardly, disgusting' ban on transgender troops Trump moves to ban most transgender people from serving in military MORE or his team, should have the contents of a grand jury leaked out into the press selectively," Graham added on Friday.

Graham and Sen. Cory Booker (D-N.J.) introduced legislation on Thursday that would require a court to sign off before the Trump administration could fire Mueller, whose probe also includes potential ties between the Trump campaign and Moscow.

The Trump administration has been beset by a constant stream of leaks since taking over in late January.

Attorney General Jeff SessionsJefferson (Jeff) Beauregard SessionsMcCabe defends himself against firing in Washington Post op-ed Attorney: Roy Moore supporters offered K, Bannon meeting to drop accuser as client Al Franken: Sessions firing McCabe ‘is hypocrisy at its worst’ MORE announced Friday that the administration would crack down on leaks, including directing more resources toward investigating leaks and reviewing Justice Department rules for subpoenaing media outlets that publish sensitive information.

The Washington Post published a leaked transcript of Trump's January phone calls with Mexican President Enrique Peña Nieto and Australian Prime Minister Malcolm Turnbull this week.

Graham added on Friday that "somebody needs to go to jail" over the leaks.

"I've never seen anything like it. ... I've never seen transcripts of the presidential phone calls in the front page of The Washington Post. How would you like to be a world leader talking to President Trump? So this undermines his ability to be [an] effective president," he said.