Senator Jeff Flake warned President Donald Trump against firing Special Counsel Robert Mueller, saying that "no one" wants to see impeachment proceedings.
Flake, an Arizona Republican who is often critical of the president, said firing Mueller would "create a Constitutional crisis."
Mueller is investigating possible Russian collusion in Trump's election victory, and is currently probing the former businessman's real estate firm.
"Congress cannot preempt such a firing," Flake said on Twitter. "Our only constitutional remedy is after the fact, through impeachment."
Flake added that neither he nor anyone else wants to see Trump or Congress go through what they did two decades ago.
In late 1998, the House filed impeachment charges against President Bill Clinton on allegations of perjury.
The Senate, of which Flake is now a member, acquitted Clinton on all charges in early 1999.
Three members of the committee tasked with considering Clinton's impeachment remain in Congress today: Rep. Jim Sensenbrenner (R-Wis.), Rep. Steve Chabot (R-Ohio) and Sen. Lindsey Graham (R-S.C.).
Graham has also called a potential Mueller dismissal an impeachable offense.
Additionally, the seat of one key Republican member of the Judiciary Committee at the time, Republican Rep. James Rogan of California, is now held by Adam Schiff (D-Calif.) - the ranking member of the House Intelligence Committee, probing Russian interference.
Schiff beat Rogan in the 2000 elections in a historically expensive contest.