Following the release of House Intelligence Committee Chairman Devin Nunes’ memo on Friday, Democratic leaders in Congress sent a letter to President Donald Trump warning him not to use the document as a reason to fire those in charge of the Russia probe — Deputy Attorney General Rod Rosenstein and special counsel Robert Mueller.

The Democrats cited reports that Trump has told friends and aides that he could use the memo to discredit the Russia probe. As the Washington Post reported, Trump told aides that the memo might give him a reason to fire Rosenstein, and he has told friends that it could prove that Mueller’s investigation is a “witch hunt.”

“We are alarmed by reports that you may intend to use this misleading document as a pretext to fire Deputy Attorney General Rod Rosenstein, in an effort to corruptly influence or impede Special Counsel Bob Mueller’s investigation,” the Democrats wrote in the letter.

“We write to inform you that we would consider such an unwarranted action as an attempt to obstruct justice in the Russia investigation. Firing Rod Rosenstein, DOJ Leadership, or Bob Mueller could result in a constitutional crisis of the kind not seen since the Saturday Night Massacre,” they added.

House Minority Leader Nancy Pelosi (D-CA) and Senate Minority Leader Chuck Schumer (D-NY) signed the letter, along with several other Democrats in Congress.

The push to release the memo has sparked concern that Trump could use it to fire Rosenstein and replace him with someone more willing to reign in Mueller’s probe. Reporting indicates Trump is unhappy with Rosenstein and has increasingly focused his anger over the Russia probe at the deputy attorney general. The President also reportedly asked Rosenstein in December whether he was “on my team.”

The full text of the letter is below: