Can the leadership of the Congressional intelligence committees get total access?

Factual Questions
1

Do the leaders of the House and Senate intelligence committees have clearance for all classified information? Can they request it at any time?

Thanks,
Rob

2

The National Security Act of 1947 states: “The President shall ensure that the congressional intelligence committees are kept fully and currently informed of the intelligence activities of the United States, including any significant anticipated intelligence activity as required by this title.”

ETA: Of course, there is other classified information beyond intelligence. For example, in the 1990s, there was an effort by some congressmen to receive briefings on nuclear war plans. AFIK, the effort was not successful.

3

So, if the committee suspects the Prez is keeping them in the dark, can they go over to the CIA (or, more realistically, call upon the DNI to testify) on a fishing expedition? How hard is it for them to determine if the President is concealing information from them?

4

From a 1997 CIA report on intelligence sharing with Congress:

https://www.cia.gov/library/center-for-the-study-of-intelligence/csi-publications/books-and-monographs/sharing-secrets-with-lawmakers-congress-as-a-user-of-intelligence/toc.htm

Also see: The Agency-and-the-Hill: CIA’s Relationship with Congress, 1946-2004

Incidentally, congressional requests are handled at CIA by the Office of Congressional Affairs.