Will executive privilege confound House prerogative? As the impeachment presentment rolls into its third day on the Senate floor, the one message that gets beaten into the ground by each House manager is the need to call witnesses who didn’t testify before the House. Adam Schiff and Jerrold Nadler declined to pursue witnesses like John Bolton and Mick Mulvaney because they didn’t want to get slowed down by a court fight over executive privilege.

Senate Republicans are asking themselves why they shouldn’t make the same choice the House did:

A growing number of Republicans are pointing to President Donald Trump’s threat to invoke executive privilege in order to make their case against subpoenas sought by Democrats for key witnesses and documents, a development that could bolster Senate Majority Leader Mitch McConnell’s goal of a swift end to the impeachment trial.

GOP senators are privately and publicly raising concerns that issuing subpoenas — to top officials like acting White House chief of staff Mick Mulvaney and former national security adviser John Bolton and for documents blocked by the White House — will only serve to drag out the proceedings. Plus, many say there’s little appetite for such a time-consuming fight, given that legal battles may ultimately not be successful and could force the courts to rule on hugely consequential constitutional issues about the separation of powers between the branches of government.

McConnell has little margin for error since it would take just four Republican defections to join with 47 Democrats in order to issue a subpoena. But his increased warnings that subpoenas could prompt an “indefinite” delay in the trial and get tied up in the courts have been gaining traction within his conference, GOP senators and aides told CNN.

It’s not really a question of a “growing number of Republicans” in the conference regarding witness subpoenas. There wasn’t much appetite for those subpoenas in the first place. The issue is whether there’s appetite among four Senate Republicans, the number that would have to flip to allow Chuck Schumer a majority to win on a floor vote for a subpoena request.

In any configuration, Schumer would have to get Lisa Murkowski to vote for a subpoena, being the most independent-minded Republican senator in the caucus. Murkowski had kept her cards close to the vest on this question, but after two days of the House managers’ arguments, she’s sounding a very skeptical note on their demands:

Democrats would need four Republicans to vote with them to successfully call a witness, and GOP senators are expressing confidence the votes are not there.

Sen. Lisa Murkowski (R-Alaska), who has been seen as a swing vote, appeared wary of a legal fight, characterizing House Democrats as trying to get the Senate to go through a legal battle they bypassed.

“It’s kind of like the House made a decision that they didn’t want to slow things down by having to go through the courts,” she said. “And yet now they’re basically saying you guys need to go through the courts. We didn’t but we need you to. That’s kind of where we are.”

Some Democrats are now claiming that executive privilege doesn’t need to be addressed by the court in an impeachment trial, noting that the Senate has the “sole” power to try the president. The Hill quotes one legal expert expressing support for that notion:

James Robenalt, an attorney with the firm Thompson Hine and an expert on Watergate, said the Constitution and Senate rules empower the upper chamber to decide questions of evidence admissibility.

“I think the Senate has the right to make its own rules and rulings,” Robenalt said. “That should keep the courts out of privilege decisions.”

Ahem. A federal district court has the power to try cases too, but defendants can appeal evidentiary rulings to higher courts as well. A single court cannot dictate rules without any oversight at all. On top of that, the executive branch is co-equal to Congress, not subsidiary to it, which means executive privilege is not within the Senate’s purview to determine. A court would have to rule on the limits of executive privilege, even within the context of an impeachment. You can bet that the courts will see it that way if Trump challenges the subpoenas on that basis, and you can bet the courts will enjoin the witnesses from appearing until the courts settle the matter.

The Senate has the sole power to try impeachments. That doesn’t mean they have the power to make up or disregard due process or ignore constitutional prerogatives or limitations. And if Democrats really thought that was the case, the House would have called Bolton and Mulvaney and had them arrested for failing to appear even if Trump went to court on executive-privilege claims.

All of this appears moot now, anyway. If Schumer has lost Murkowski on the witness issue, it’s game over, man. At worst, Mitch McConnell would end up 50-50 on subpoena demands, which would put a spike through them. Senate Democrats will remain stuck with the half-baked case the House dropped on them, one that was destined to go nowhere anyway.