Mr. Trump could still move to block the testimony next week, given his history of changing his mind at the last minute about major decisions. But legal experts have said that Mr. Trump has a weak case to invoke executive privilege because he has publicly addressed his conversations with Mr. Comey, and any such move could carry serious political risks.

One of the administration officials said Friday evening that Mr. Trump wanted Mr. Comey to testify because the president had nothing to hide and wanted Mr. Comey’s statements to be publicly aired. The officials spoke on the condition of anonymity because they did not want to be identified discussing a decision that had not been announced…

Invoking executive privilege can be a politically treacherous move, recalling past scandals like Watergate, in which President Richard M. Nixon asserted the power in efforts to block congressional investigations. President Barack Obama used the legal authority once, during congressional inquiries after weapons ended up in the possession of Mexican gun cartels.