Senate Minority Leader Chuck Schumer, D-N.Y., on Saturday warned Republicans that their efforts to uncover the identity of a secret FBI source in a possible attempt to undermine special counsel Robert Mueller's investigation is nearing a legal line.

Schumer tweeted support of Sen. Mark Warner's, D-Va., statement cautioning Republicans to stop pressing the Justice Department for more information about a source that is presumed to have helped the FBI and Mueller's probe into potential Trump campaign dealings with Russia.

" @MarkWarner’s statement here is on the money and a severe warning to right wing Republican Congressmen who are trying to obstruct Special Counsel Mueller’s investigation and could be coming close to crossing a legal line," Schumer tweeted on Saturday.

Warner, the top Democrat on the Senate Intelligence Committee, warned that Republicans could be breaking the law in their pursuit.

“It would be at best irresponsible, and at worst potentially illegal, for members of Congress to use their positions to learn the identity of an FBI source for the purpose of undermining the ongoing investigation into Russian interference in our election,” Warner said in a statement Friday night. “Anyone who is entrusted with our nation’s highest secrets should act with the gravity and seriousness of purpose that knowledge deserves.”

House Intelligence Committee Chairman Devin Nunes requested details related to the covert source, but was denied by the Justice Department on grounds that releasing such information could endanger lives and pose a risk to national security. Nunes and other Trump allies say they aren't concerned about the source's identity but the source's role in the investigation.

Trump pushed the issue in a tweet Friday, repeating the unverified claim that an informant worked their way into his campaign.



Reports are there was indeed at least one FBI representative implanted, for political purposes, into my campaign for president. It took place very early on, and long before the phony Russia Hoax became a “hot” Fake News story. If true - all time biggest political scandal! — Donald J. Trump (@realDonaldTrump) May 18, 2018



Warner and Schumer aren't the only ones warning Republicans. FBI Director Christopher Wray issued a word of warning to Congress during his testimony to the Senate Appropriations Committee.

"The day that we can't protect human sources is the day the American people start becoming less safe," Wray said Wednesday.