President Clinton is in his native state of Arkansas this weekend, but the man who for months stood at his shoulder, charged with protecting his life, is not.

Larry Cockell, the Secret Service agent who heads the president's protective detail, was forced to remain in Washington awaiting a summons to appear before a grand jury investigating whether Clinton carried on a sexual affair with Monica Lewinsky, a former White House intern, and then lied about it.By bringing Cockell and seven other Secret Service agents to the federal courthouse in Washington, the Whitewater independent counsel, Kenneth Starr, made a powerful legal and visual statement about the authority of his office. And while it is hazardous to predict the course of any investigation, it appears that Starr is entering a decisive phase of the inquiry.

Although questions remain on lawyer-client privilege and the assertion of a broad new privilege governing Secret Service testimony, prosecutors now have an opportunity to question officials and agents of the Secret Service about what they may have seen or heard regarding Clinton and Lewinsky.

After a week of legal maneuvering, Starr on Friday won the right to question Cockell and seven other Secret Service agents when Chief Justice William Rehnquist rejected a plea by the Justice Department to shield the agents from questioning.

But the chief justice said the Supreme Court might yet decide to hear the department's appeal of lower court rulings that denied an administration claim that Secret Service personnel are protected from having to testify regarding the president by an untested "protective function privilege."

Clinton said Friday that it would be inappropriate for him to comment on the Secret Service subpoenas and the reassignment of his hand-picked chief bodyguard, Cockell. But aides said that the president is seething at what he considers a violation of the intimate and confidential relationship he must have with those assigned to guard him.

One Democratic ally of the president said that Clinton believes the subpoenas were a vindictive act by Starr designed to embarrass the president and humiliate the Secret Service, and he predicted a strong public backlash against Starr. Starr has denied any political motives, saying he seeks only "the truth."