There were faint but encouraging signs over the weekend that at least some congressional Republicans are prepared to join Democrats in drawing against a red line against any move by President Trump to fire special counsel Robert Mueller and end his investigation of Russian meddling in the 2016 election.

As Trump launched a new Tweetstorm against the investigation and his lawyer, John Dowd, called for the probe to be shut down, a cadre of GOP lawmakers warned the president to think twice before acting.

“If (Trump) tried to do that, it would be the beginning of the end of his presidency,” Sen. Lindsey Graham, R-SC, said of any move against Mueller. “We are a rule-of-laws nation.”

“Mr. Mueller and his team should be able to do their job.” House Speaker Paul Ryan, R-WI, said in a statement released by his office.

“I don’t know what the designs are on Mueller,” said Sen. Jeff Flake, R-AZ, “but it seems to be building toward that (firing him), and I just hope it doesn’t go there, because it can’t. We can’t in Congress accept that.”

“The special counsel’s investigation should be allowed to continue uninterrupted,” said Sen. Charles Grassley, R-IA, the chairman of the Senate Judiciary Committee.

Other GOP lawmakers, including Sen. Marco Rubio, R-FL, and Rep. Trey Gowdy, R-SC, had other investigation-related criticisms of the president. On “Meet the Press,” Rubio said Attorney General Jeff Sessions’ should not have agreed to Trump’s call for the firing late Friday of Andrew McCabe, the former deputy director of the FBI. McCabe was dismissed just hours before he would have become eligible for his pension; Trump has accused him of short-circuiting the bureau’s investigation of former Secretary of State Hillary Clinton’s use of a private email server to do State Department business.