McCarthy, a Fox News contributor and former Assistant U.S. Attorney for Manhattan, said that the political and legal declarations coming from both Rep. Adam Schiff, D-Calif., and White House Counsel Pat Cipollone are not helping their prospective sides.
In Schiff's case, McCarthy said the House Intelligence Committee chairman has continued to argue that the White House must provide more evidence and witnesses, which he was referred to as "key," "vital" or "crucial."
At the same time, Mccarthy noted, the impeachment managers argue that the evidence against Trump is "overwhelming."
McCarthy wondered aloud how it is possible for a case against Trump to be "overwhelming" if it is also lacking "vital" evidence and "key" witnesses.
"I think his rhetoric is running into his position," McCarthy said.
Meanwhile, Cipollone's team has argued what McCarthy called "the constitutional infirmity" of the Democrats' two impeachment charges.
"The president wants to contest the facts of the case. Some of that has seeped into the rhetoric of his lawyers," said McCarthy, who added that such rhetoric does not help any case to dismiss the charges outright.
That rhetoric, he said, also concerns moderate Republican senators like Cory Gardner of Colorado, Thom Tillis of North Carolina and Susan Collins of Maine, who are up for reelection this year and who are being closely watched as the trial drags on.
"The president is taking the position that the facts need to be contested -- that whether there was a quid pro quo and whether he did anything wrong needs to be contested," McCarthy said. "That actually supports the argument for why you should hear from witnesses who haven't been heard from yet and who may have things to say that are relevant on those different subjects.
"Now, [Republicans] can make the argument that the House should have called those witnesses or made a better effort to get them. The fact is that the rhetoric of contesting the facts is supporting the arguments of the people who say that more witnesses are necessary."