House Democrats' handling of the Trump impeachment to date may be turning off Republicans -- notably, those seen as possible defectors in a final vote.

The first sign of a backlash among that critical group came Wednesday when Sen. Lisa Murkowski, R-Alaska, a moderate member of the conference, said she was offended by House manager Rep. Jerrold Nadler’s assertion that GOP members voting against allowing new testimony and evidence were engaged in a “cover-up.”

AT SENATE IMPEACHMENT TRIAL, RESTLESS LAWMAKERS STRUGGLE TO SIT THROUGH SCHIFF'S OPENING ARGUMENT

“I took it as offensive,” she told reporters Wednesday. “As one who is listening attentively and working hard to get to a fair process, I was offended.”

Nadler’s opening statement, which led to U.S. Chief Justice John Roberts admonishing those in the chamber, accused Republican senators of “voting for a cover-up, voting to deny witnesses, an absolutely indefensible vote, obviously a treacherous vote.”

Murkowski’s complaint about Nadler's remarks is particularly noteworthy, as she is among the small group of Republican senators seen as a possible swing vote on impeachment and a possible supporter of allowing more witness testimony later on in the trial.

But Murkowski is not alone—Sen. Josh Hawley, R-Mo., on Wednesday said Democrats “took a huge step backward” in their opening.

“I mean, that’s an extraordinary thing to say on the floor of the United States Senate, the middle of the trial, and that’s what drew the rebuke and rightly so,” Hawley told reporters. “I can tell you, there was an open, open gasping on the Senate floor when Nadler was saying these things. I mean, it’s really, really extraordinary.”

He added: “If the goal was to persuade, they took a huge step backward last night.”

Meanwhile, senators, in general, have already shown some restlessness on the floor after hours and hours of opening statements from the prosecution.

“The House is completely miscalculating how to handle this,” a Senate GOP source told Fox News Thursday. “They’re putting far too much emphasis on the time they use than the substance of what they’re delivering.”

“You just have to stretch and you just got to stand,” Murkowski said of the restlessness during the speech from lead House Manager House Intelligence Committee Chairman Adam Schiff, D-Calif.

“Those chairs, they look nice, [but] they are not comfortable chairs.”

Murkowski, who is no stranger to having to sit still with her regular D.C.-to-Alaska commute, said even she had a hard time remaining stationary during the Senate trial.

“I sit on an airplane for 10 to 12 hours usually twice a week,” Murkowski said. “I’m used to kind of sitting in small confined spaces. But these chairs are not comfortable.”

Murkowski said she is resorting to some of her plane exercises to manage sitting through the Senate trial.

“I got a little bit of sciatica going on. I’m doing all my airplane yoga sitting in the chair there, trying to stretch, trying to move without moving. It’s hard,” she said.

Sen. Mike Braun, R-Ind., also said empty chairs during the opening statements were not a symptom of disrespect, but rather, discomfort.

“I think you need to move around,” he said. “I stand up half the time. And everybody’s got their own way now of getting through what’s going to be a long, kind of taxing experience.”

In the second full day of President Trump's impeachment trial, senators broke up long stretches of listening to the House Democrats' case by taking bathroom breaks, stretching out and sneaking a few snacks from the well-stocked cloakrooms.

“Maybe some are conferring. Others are probably heading for the snacks that are in the cloakroom,” said Sen. Pat Leahy, D-Vt., who headed up to the third-floor gallery during a recess to meet his wife, who was watching from the balcony.

Fox News' Marisa Schultz and Jason Donner contributed to this report.