Specifically, legal experts say that Trump will have a weak case if he tries to block Bolton's testimony by asserting executive privilege.
Michael Stern, a former lawyer for congressional Republicans, tells Reuters executive privilege likely won't cover witness testimony at an impeachment trial, especially when Bolton's testimony is "clearly critical to issues before the Senate, and that outweighs any privilege that applies."
Stern also says that Trump would be foolish to file a lawsuit aimed at blocking Bolton's testimony if 51 senators vote in favor of subpoenaing him.
"He won’t win, legally, and it could backfire politically,” Stern said. “Once the majority of senators have said they want to hear from Bolton, going to court is just going to rub senators the wrong way.”
Constitutional scholar Mark Rozell similarly believes that Bolton could testify without revealing any critical national security information.
"To me, it looks like the president is just trying to protect himself," he said.