The statements indicate the Bush administration will not be able to count on full support from the 10 committee Republicans when the hearings begin in early February.
The judiciary committee also has eight Democrats, who have questioned the legality of the surveillance program.
Senator Dianne Feinstein, one of the Democratic members, reiterated her doubts Sunday, saying, "I do not believe it's true that the president's plenary power would allow him to simply avoid the law."
If a plenary power exists, that is the law.
When asked what could happen if lawmakers find Bush in violation of the law, Specter answered: "Impeachment is a remedy. After impeachment, you could have a criminal prosecution, but the principal remedy ... under our society is to pay a political price."
He made it a point to clarify, however, that he was speaking theoretically and was "not suggesting remotely that there's any basis" for a presidential impeachment at this moment.