A friend of Mr. Kissinger said tonight that he had originally accepted the job in the spirit of public service and out of unwillingness to say no to the president, never anticipating that his client list would become such a point of contention. But after Democrats, newspaper editorials and family members demanded the disclosure, Mr. Kissinger was faced with the question of breaking the confidentiality agreements he has signed with his clients.

``If you have confidentiality agreements, you can't just throw them away,'' said the friend, who would speak only if not identified. Many clients do not want competitors to know who is advising them or how they are operating strategically, the friend noted, and Mr. Kissinger, by the same token, forbids clients from using his name to lobby governments. ``He owed it to his clients not to have them dragged into this,'' the friend said.

But Senator Harry M. Reid of Nevada, the Senate Democratic whip, said it was inevitable that someone with Mr. Kissinger's global ties would have to step down from a commission looking into the conduct of foreign countries and domestic intelligence agencies.

``There were too many conflicts of interest for him to lead this task,'' said Mr. Reid, who is chairman of the Ethics Committee that issued the final opinion on disclosure. ``I knew he would never disclose that information. Now the country and the families deserve someone who won't be afraid to lead this commission.''

Mr. Reid criticized the White House for trying so hard to protect Mr. Kissinger's privacy.

``The pressure put on the Ethics Committee by the White House was really untoward,'' he said. ``They were calling and berating our staff, saying he didn't have to file because he worked for the executive branch. I mean, come on. What were they trying to hide? Finally he realized he couldn't hide it anymore.''

Mr. Kissinger's friend said there were ``no deep dark secrets'' on the client list, with no clients in the Middle East or in government.

Leaders of the families who fought to create the commission said they were not particularly disappointed by the resignation, because they were never very comfortable with Mr. Kissinger's past as the insider and by his widespread financial ties.