But Thune also conceded on Wednesday that the first round of details could be damaging after Taylor, the U.S. envoy to Ukraine, testified that Trump refused to release military aid and hold a White House meeting with the Ukrainian president unless he probed Trump’s political opponents.

“The picture coming out of it based on the reporting we’ve seen is, yeah, I would say it’s not a good one,” Thune told reporters. “But I would say also, until we have a process that allows for everybody to see this with full transparency, it’s pretty hard to come to hard and fast conclusions.”

He said that the House Democrats’ “rigged,” closed-door testimony “really affects the credibility of this impeachment process” and that Taylor’s interviews with investigators should be made available for all to see.

It’s a possible sign that the Senate Republicans who will determine whether Trump is removed from office in any impeachment trial aren’t ready to break with him just yet. But it also suggests that Republicans may be more comfortable fighting on process grounds rather than substance, given they don't know what might emerge next.

Sen. Cory Gardner (R-Colo.), who has said he wants to get to the bottom of what happened with Ukraine, also complained that he’s been unable to read the transcripts.

Sen. Lisa Murkowski (R-Alaska) even took a reporter’s copy of Taylor’s opening statement and questioned why the House committees hadn’t circulated it themselves.

“How did you get this? Are the committees releasing it? I mean, even the opening statement? Do you think that’s problematic,” she asked. “You guys are trying to report, you’re trying to tell me what was said. But you don’t have it firsthand you don’t have it firsthand, so how do we know what’s going on?”

Murkowski has expressed discomfort with the prospect of tying aid to an investigation of former Vice President Joe Biden and is not exactly the closest of allies with the president.

Staunch Trump backers were even harsher toward Democrats.

“This is a one side show trial, don’t they do that in Russia?” said Sen. David Perdue (R-Ga.). “How could anybody be concerned about it until they hear the counter?”

Marianne LeVine contributed to this report.