WASHINGTON -- Supreme Court nominee Samuel A. Alito Jr. was warned yesterday by two key senators that he will be expected to comment on the revelation that President Bush authorized the National Security Agency to monitor the international phone calls and e-mails of U.S. citizens without seeking a court order.

In separate letters to Judge Alito, Sens. Arlen Specter, R-Pa., the chairman of the Judiciary Committee, and Patrick Leahy, D-Vt., its ranking Democrat, told the nominee to expect questions about the surveillance program, which Mr. Leahy said "is but one of several areas where the court's role as a check on overreaching by the executive may soon prove crucial."

In his letter, Mr. Specter stopped short of asking Judge Alito if Mr. Bush violated the Constitution by authorizing surveillance of persons thought to have ties to al-Qaida without obtaining a warrant from the Foreign Intelligence Surveillance Court.

But the Pennsylvania Republican said he might ask Judge Alito what "jurisprudential approach" the nominee would employ in deciding whether Mr. Bush could legally order warrantless surveillance by virtue of his constitutional power as commander-in-chief or under a Sept. 14, 2001, congressional resolution authorizing "all necessary and appropriate force" against terrorists.

Mr. Specter's most pointed questions -- and thus the ones Judge Alito might be most reluctant to answer -- concern Hamdi v. Rumsfeld, a decision by the Supreme Court last year holding that U.S. citizens held as "enemy combatants" had a right to challenge their detention in court.

Mr. Specter asked Judge Alito if he agreed with an opinion by Justice Sandra Day O'Connor in that case that "war is not a blank check for the president."

Mr. Specter then asked: "In light of Justice O'Connor's statement, what jurisprudential theory would you invoke to evaluate the limits on the president's authority to conduct surveillance on U.S. citizens? . . . Pursuant to the Supreme Court's rationale in Hamdi, would it be permissible for the president to engage in electronic surveillance or other means to protect national security without further congressional action?"

In all, Mr. Specter posed 12 questions to Judge Alito, several of them designed to explore the nominee's views on the relationship between congressional and executive power in wartime. Article I of the Constitution gives Congress the power to "declare war," but Article II makes the president "commander-in-chief."

Mr. Specter asked Judge Alito if Congress unconstitutionally delegated its power to declare war to Mr. Bush when it voted in 2002 to authorize future military action against Iraq.

Some of Mr. Specter's questions will require Judge Alito to brush up on his history. For example, the senator asked the nominee whether the Korean and Vietnam wars "should have, as a matter of constitutional law, required a declaration of war by Congress."

Yesterday's letter was the third in which Mr. Specter has provided Judge Alito with what he called "advance notice of some lines of inquiry I may follow at your confirmation hearing," which begins Jan. 9. Previously he asked the nominee about his views of precedent, the rights of criminal defendants and the scope of freedom of religion under the First Amendment.

Sens. Specter and Leahy weren't the only ones to link the Bush surveillance program and the Alito nomination. The leader of a liberal group that has criticized the nomination said yesterday that if confirmed, Judge Alito likely would uphold such surveillance.

"Judge Alito's statements, speeches and judicial record taken together establish that he supports an extremely broad interpretation of the president's powers under the Constitution, and of the powers of executive branch law enforcement officers," said Ralph Neas, president of People for the American Way.

"It is hardly a surprise that a president who has repeatedly claimed unprecedented power would nominate an individual with these pro-executive views to the court that has the last word on presidential authority and on the Fourth Amendment."