Republican lawmakers vowed that the presidential transition after November’s election will occur without disruption, in a rebuke to President Donald Trump’s refusal to commit to a peaceful transfer of power.

“The winner of the November 3rd election will be inaugurated on January 20th,” Senate Majority Leader Mitch McConnell tweeted Thursday morning. “There will be an orderly transition just as there has been every four years since 1792.”

Trump said Wednesday that “we’re going to have to see what happens,” in response to a reporter’s question at a White House news conference about a peaceful transfer of power. “You know that I’ve been complaining very strongly about the ballots, and the ballots are a disaster.”

The president has raised questions about the security and legitimacy of mass mailed-in ballots, without offering evidence.

FBI Director Christopher Wray told a Senate Homeland panel hearing Thursday that the FBI has seen no evidence of an organized voter fraud effort that could change the results of a presidential election.

“Certainly to change a federal election outcome by mounting that kind of fraud at scale would be a major challenge for an adversary,” Wray said.

The Federal Bureau of Investigation also put out a warning Thursday against voter fraud, including tampering with ballots or voting more than once. Trump at one point urged his supporters to attempt to vote in-person after casting mail-in ballots in order to make sure their votes were counted.

“The FBI is asking each citizen to remain vigilant and report any suspected criminal scheme targeting voters to the FBI immediately,” Wray said in the statement.

Democrats including House Speaker Nancy Pelosi and Senate Minority Leader Chuck Schumer expressed alarm at Trump’s comments, with Schumer calling the president “the gravest threat to American democracy.”

“It’s very sad that you even have to ask that question,” Pelosi said at a news conference Thursday on whether there would be a peaceful transfer of power. “It would not be a good thing in our country for our election to be ignored by the president.”

Schumer accused Trump of saying that if he wins, the election is legitimate and if he loses it’s rigged, and he might just stay in office and not count the ballots.

“Any suggestion that a president might not respect this Constitutional guarantee is both unthinkable and unacceptable,” Senator Mitt Romney of Utah, the Republican Party’s 2012 presidential nominee, said in a Twitter post on Wednesday.

Senator Richard Shelby, an Alabama Republican, didn’t directly criticize Trump for his remarks but told reporters he’s confident there would be a peaceful transfer.

“We’ve always had a peaceful transfer of power,” Shelby said. “That’s one of our hallmarks. And I think this year will be no exception.”

Senator Mike Rounds, a South Dakota Republican, said the real issue is whether supporters of Democratic nominee Joe Biden will accept the outcome when Trump wins a second term.

“I think his message was crystal clear, he expects to win so he doesn’t have to worry about that,” Rounds said, who dismissed the idea that Republicans need to send the president a message calling in him to respect the electoral process.

Representative Liz Cheney of Wyoming tweeted Thursday: “The peaceful transfer of power is enshrined in our Constitution and fundamental to the survival of our Republic. America’s leaders swear an oath to the Constitution. We will uphold that oath.”