As most Republicans have come out in support of President Trump following his indictment this week on charges related to the events of January 6, 2021, one-time Senate critics of Mr. Trump and his alleged role in the riot at the Capitol have fallen silent, with only Senator Murkowski openly criticizing the former president.

In the House, members were quick to come to Mr. Trump’s defense. Speaker McCarthy framed the indictment as an attempt to distract from the “news,” likely referring to the ongoing investigation of President Biden’s son, Hunter Biden, and claimed that it is an attempt to “attack the frontrunner for the Republican nomination.”

Senate Republicans, though, appear divided, with some senators coming to Mr. Trump’s defense and others keeping their opinions largely to themselves.

Ms. Murkowski has been one of the most vocal critics of Mr. Trump in the Senate since the indictment, calling on Americans to read the indictment and saying, “I voted to impeach former President Trump based on clear evidence that he attempted to overturn the 2020 election after losing it.”

“Additional evidence presented since then, including by the January 6 Commission, has only reinforced that the former President played a key role in instigating the riots, resulting in physical violence and desecration of the U.S. Capitol on January 6, 2021,” Ms. Murkowski said.

Minority Leader McConnell, on the other hand, has been silent. Mr. McConnell has long had a strained relationship with Mr. Trump and, during Mr. Trump’s second impeachment trial, said, “He didn’t get away with anything yet — yet.” Mr. McConnell’s office did not immediately reply to a request for comment.

“We have a criminal justice system in this country,” Mr. McConnell said when he voted to acquit Mr. Trump during the second impeachment. “We have civil litigation. And former presidents are not immune from being accountable by either one.”

The minority whip in the Senate, Senator Thune, had said last week that he thought “laws were broken” and that “you’ve got to make sure you support — you allow the justice system to work.” Since then, though, he has been silent.  Mr. Thune’s office did not immediately respond to a request for comment.

A potential successor to Mr. McConnell as Republican leader, Senator Cornyn, on the other hand, repeated a common Republican line, saying that “our system of justice has a double standard.”

“I think all you need to do is look at the difference in the way that the Hunter Biden investigation and the plea bargain that collapsed,” Mr. Cornyn said.

These two responses have become emblematic of the two sorts of positions that Senate Republicans are staking out. On one side, senators who have been critical of Mr. Trump are maintaining silence, and on the other, senators who support Mr. Trump have reiterated that support.

Senators like Mike Lee and Shelley Moore Capito, who were critical of Mr. Trump’s involvement in January 6 at the time, have been mum on the topic since the indictment was delivered. Neither Mr. Lee nor Ms. Capito’s offices immediately replied to a request for comment.

In January 2021, Senator Tillis said that Mr. Trump “shares responsibility for the disgrace that occurred on January 6,” but maintained that “an impeachment trial is not the best or only way to hold a former elected official accountable for their actions.”

Mr. Tillis has yet to weigh in on the indictment of Mr. Trump. The silence from senators who have been historically critical of Mr. Trump for his role on January 6 stands out compared to the defense of Mr. Trump from his stalwarts. Mr. Tillis’s office did not immediately reply to a request for comment.

One of Mr. Trump’s most powerful supporters in the Senate, Senator Barrasso, was the highest-ranking Republican to issue a statement, reiterating claims of a “two-tiered” justice system.

“The American people have lost faith in Biden’s Justice Department,” Mr. Barrasso said. “They are uncomfortable watching the current president weaponize the justice system against his political opponent.”

Other supporters of Mr. Trump, like Senator Cruz, have claimed that the indictment is an attempt at “election interference by the Biden Department of Justice.”

“Whenever there’s a new development against Hunter and the Biden family, this politicized DOJ attacks Trump,” Mr. Cruz wrote in a statement. “And the media happily pivots to echo the Trump attacks.”