Congressional Democrats reacted with shock and alarm to Tuesday’s firing of James Comey, accusing President Donald Trump of ousting the fiercely independent FBI director to escape scrutiny over his campaign’s Russia ties.

Republicans offered more muted responses, saying the president has a right to fire Comey and that congressional investigations into Russia’s election meddling would not be impeded by his dismissal.

Senate Democratic Whip Dick Durbin said Comey’s firing would “absolutely” ramp up Democratic calls for a special prosecutor to investigate the Trump campaign.

“I don’t think there’s any alternative at this point,” Durbin said. “I worry that they’ll refuse the special prosecutor and we’ll never hear again from the FBI investigation.”

Trump on Tuesday reached out to key senators, including Judiciary Committee ranking member Dianne Feinstein (D-Calif.) and subcommittee chairman Lindsey Graham (R-S.C.), to inform them of the decision.

Some senators said they couldn’t believe the news.

“I’m speechless right now,” Sen. Joe Manchin (D-W.Va.) said immediately after being informed by an aide in a Senate hallway. Sen. Marco Rubio (R-Fla.), a leading Russia hawk who has been critical of Trump, said he learned the news while presiding over the Senate and that he was “surprised.”

“It certainly wasn’t something that had been speculated about,” he said.

In a statement, Feinstein said she got a call from Trump at 5:30 p.m. to inform her of the news. She urged Trump to appoint a successor who is “strong and independent.”

Senate Majority Leader Mitch McConnell said, “Once the Senate receives a nomination, we look forward to a full, fair, and timely confirmation process to fill the Director position. This is a critical role that is especially important as America faces serious threats at home and abroad.”

Sen. Chuck Grassley (R-Iowa), who chairs the Judiciary panel that will oversee the nomination process for Comey’s successor, said public trust and confidence in the FBI had been lost under Comey because of his handling of controversial matters, including the Hillary Clinton email probe.

“The FBI Director serves at the pleasure of the president,” Grassley said. “Under these circumstances, President Trump accepted the recommendation of the Justice Department that the Director lacked the confidence needed to carry out his important duties.”

Graham said he appreciated Comey’s service but that he backed Trump’s decision.

“Given the recent controversies surrounding the director, I believe a fresh start will serve the FBI and the nation well,” he said. “I encourage the president to select the most qualified professional available who will serve our nation’s interests.”

But a number of Democrats said the firing raised serious concerns.

“Donald Trump’s decision to fire him now, in the midst of an investigation into Trump associates and their ties to Russia, is outrageous,” said Sen. Ron Wyden (D-Ore.), a member of the Senate Intelligence Committee. “There can be no question that a fully independent special counsel must be appointed to lead this investigation. At this point, no one in Trump’s chain of command can be trusted to carry out an impartial investigation.”

Sen. Bill Nelson (D-Fla.) said that “now it is more clear than ever that we need an independent commission to get to the truth of Russia’s interference with our election.”