The upheaval surrounding Vice President Gore's presidential candidacy continued yesterday when Ronald A. Klain, the vice president's chief of staff, announced his resignation to become a partner in the Washington office of a prominent California law firm.

Klain's departure after nearly four years on the job is another blow to the vice president, whose campaign has struggled through a series of staff changes and other problems throughout spring and summer.

Gore, who informed his staff of the decision at a late-afternoon meeting yesterday, said Klain would serve as an unpaid senior strategist to his campaign. He said Klain would provide continuing advice and take on special projects.

Gore also announced that his current counsel, Charles Burson, a longtime friend from Tennessee, would succeed Klain as chief of staff.

Klain said in an interview that he had informed Gore earlier this year that he intended to leave before the end of the presidential campaign and that he had informed the vice president on June 20 the time had come to move on.

But Democratic sources said the timing was influenced by the arrival of Tony Coelho as Gore's campaign chairman, an appointment that signaled a shift in power from Gore's vice presidential staff to the campaign operation and a diminishment in the role of the chief of staff. Klain had been instrumental in helping to organize the early stages of Gore's presidential campaign and oversaw the vice president's political activities during that period.

"Clearly when the center of power moved from the vice president's official office to the campaign, that added a new variable to the dynamic," one Democrat said. "Given that structure, I just think it made a lot of sense for Ron" to depart.

Klain denied there was any friction with Coelho and said both the vice president and the campaign chairman had worked hard to dissuade him from leaving. "Tony tried very hard to get me to stay," Klain said. "I think Tony's going to do a great job. I'm looking forward to working with him on the outside. But this was a personal decision."

Gore praised Klain for his intelligence and loyalty, adding in a statement, "I have never known any person with a sharper mind and stronger strategic skills."

Coelho said he "wished Ron was staying and he knows it" and said he was pleased that Klain would continue to help but added that Klain was presented with an offer "he couldn't turn down."

Klain, who previously served the Clinton administration as an associate White House counsel and as chief of staff to Attorney General Janet Reno, will become a partner in the firm of O'Melveny & Myers, a Los Angeles firm.

Burson is a former attorney general of Tennessee who joined Gore's staff two years ago and has, in the words of one Democrat, "the vice president's ear, trust and friendship."