During today's confirmation hearing in the Senate Armed Services Committee, Senator Graham (R-SC) grilled former Senator Chuck Hagel about a variety of matters, including Hagel's failure to sign a letter circulated in 2000 regarding Israel. The text of that letter is available online here. What is not available online, it seems, is the AIPAC press release lauding the letter, dated October 13, 2000.
Happily, that press release still exists in my files and can be viewed here. Notably, that press release opens with the following:
[18 October update: The final number of signatories is 96. Senators Hagel (NE) and Gregg (NH) could not be reached by last Friday's deadline and they have not requested to be added to it. Abraham (MI) and Byrd (WV) were the only Senators who chose not to sign.]
So in answer to Sen. Graham's determined desire to know why Hagel refused to sign the letter - according to AIPAC (at the time), he didn't.
UPDATE: A version of this same press release, circulated a couple of days earlier, is still available online in the archives of IMRA (which also circulated the later release). That earlier version, which includes a similar intro in brackets, can be viewed here.