Top congressional Democrats told President Trump on Friday that using the new House Intelligence Committee memo as a pretext to fire Deputy Attorney General Rod Rosenstein and therefore halt the Russia investigation would spark a “constitutional crisis.”

Senate Minority Leader Chuck Schumer of New York and House Minority Leader Nancy Pelosi of California said in a letter they are “alarmed” at reports that Trump may use the memo “as a pretext” to fire Rosenstein “in an effort to corruptly influence or impede” special counsel Robert Mueller’s investigation.

“We write to inform you that we would consider such an unwarranted act 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 a kind not seen since the Saturday Night Massacre," they said.

Rosenstein is the only Department of Justice official who can remove Mueller, and he was expected to be named in the four-page classified memo made public Friday.

However, Rosenstein is only named twice in the House Intel memo: when he signed off on one renewal of a federal court surveillance warrant against former Trump adviser Carter Page and as someone who worked “closely” with former Associate Deputy Attorney General Bruce Ohr.

Ohr was demoted after it was revealed by House investigators that he met with Glenn Simpson, the co-founder of opposition research firm Fusion GPS. Fusion GPS then used funds from the Hillary Clinton campaign and the Democratic National Committee to hire Christopher Steele to compile the Trump-Russia dossier.

House Intelligence Committee Ranking Member Adam Schiff of California also signed the letter.

Other signers of the letter include Democratic Reps. Steny Hoyer of Maryland, Joe Crowley of New York, and Jerry Nadler of New York.

Senate Intelligence Committee Ranking Member Mark Warner of Virginia and Senate Judiciary Committee Ranking Member Dianne Feinstein of California signed it, as did Sen. Dick Durbin of Illinois.