The question of the President's Article II power aside, Sen. Feinstein's position that such a power can be bound by FISA or any other legislation seems self-evidently wrong. If the President has the Constitutional authority, Congress cannot change the fact.
The President has some recent precedent on his side. In 2002, the three judges of the FISA Court of Review addressed the issue in In re: Sealed Case. The FISA courts had been impeding the Justice Department's initiation of new policies concerning the Patriot Act, i.e. tearing down "the wall" between intelligence officials and criminal investigators erected by the Clinton Justice Department. The Court of Review ruled in favor of the administration as the FISA courts had no grounds upon which to direct internal Justice Dept. policy. Basically, the FISA courts were exceeding their constitutional bounds. They had no constitutional authority to direct the executive branch nor did Congress. The Court went on to refer to an older case, Truong, stating, "The Truong court, as did all the other courts to have decided the issue, held that the President did have inherent authority to conduct warrantless searches to obtain foreign intelligence information... FISA could not encroach on the President's constitutional power." The Supreme Court refused to take the case.
It is also interesting to note that the New York Times sat on the story for a year. Its release was conveniently timed with debate over the reauthorization of the Patriot Act and the release of a Times' reporter's anti-administration book, one topic of which was "domestic spying". Further, members of Congress had been alerted to the program multiple times and voiced no concern. Rep. Jane Harman, the ranking Democrat on the House Intelligence Committee, said she had been briefed on the program since 2003 and thought it was "essential to US national security." When the Times finally ran the story and the "scandal" hubbub began, Harman changed her tune.
There was plenty of media outcry about the arguably less dangerous Valerie Plame leak. What is not getting much play in the media is the danger caused or that could be caused by leaks about the NSA program. Hmm... I wonder why...