It was mid-afternoon last Monday. The president's doctors had yet to report on the results of the biopsy. The local rumor foundry was going full blast. Would the president be able to serve out a full second term? Was it more serious than it sounded? Assuming the best, who would be In or Out (with access limited) while the president convalesced?

Nancy Reagan's influence would surely grow. White House Chief of Staff Donald Regan was everywhere in evidence, taking charge. But where was the vice president, the nation's second-highest-ranking elected official, the designated crisis manager?

He was quietly at work in his part- time quarters in the Executive Office Building, across the way from the White House. His short stint as acting president had been the same as any Saturday afternoon: "Almost anytime, it's quiet." The postoperative prognosis "sounded so upbeat" that the experience "didn't seem quite as traumatic as it might have been." He was keeping his appointments -- including an interview concerning his recent European trip.

Bush is not known as a team player for no reason. So some discount must be made for the deference vice presidents pay to presidential policies. Even so, his sometimes laconic, sometimes intense, but also understated and pragmatic way of presenting the administration's case gave me a clear sense that he would conduct the same general policies in a different way.

He speaks in terms of "mechanics" far more often than in terms of grand ideological design. Nowhere is this more evident than in his approach to the problem of terrorism and to the mission of the counterterrorism task force he is assembling at Reagan's request and in response to the hostage- taking from TWA Flight 847. The president poses the threat as a declaration of war against the United States by a "confederation" of terrorist states -- and calls on America's friends and allies to join together in a global counterattack.

Bush emphasizes the limits as well as the possibilities. He is concerned about overinflated expectations (a characteristic concern, apparently, for he expresses the same worry about expecting too much from the Reagan-Gorbachev summit in November). He doesn't expect to "reinvent the wheel" in the three to six months he thinks it will take for his task force to pull together a policy within the U.S. government that our allies will accept.

From Europe, Bush brought back sobering impressions. There is heightened allied concern, as a consequence of TWA Flight 847. But it is accompanied by sharply differing perceptions of the terrorist threat, the more so when an effort is made to present it as all of a piece: "When you talk to (British Prime Minister) Margaret Thatcher, she is talking about Ireland." When he talked to the top people at the North Atlantic Treaty Organization headquarters in Brussels, they were worrying about terrorism directed against NATO installations. Oversimplification of the problem, he concluded, introduces political "barriers" to collective countermeasures.

Libya's Col. Muammar Qaddafi is on Reagan's list of "misfits, Looney Tunes and squalid criminals." But he is also on the list of oil suppliers to some of America's best friends. Thus, some European allies would argue, says Bush, that even though Qaddafi is "organizing and training terrorists and that's bad, you can't isolate him entirely because of this."

Some of the Europeans he talked to, Bush reports, are also not all that eager to get on terrorist hit lists by associating themselves too closely with the U.S.-Israeli connection. So what's needed is a definition of "terrorism" narrow enough to be accepted by the largest possible segment of the international community.

A major purpose of his task force, then, will be to identify the acts of terrorism (hijacking, indiscriminate bombings, hostage-taking) that the United States and its allies will accept as such "without getting caught up in our friendship and strategic relationship with Israel and somebody else's commercial relationship with Libya."

Another purpose will be to reconcile differences with the U.S. government on when, how and where to retaliate. Bush is convinced that "swift retribution could not help but inhibit" future terrorist acts. But the question remains: "How do you make it surgical?"

That leaves Bush squarely in the middle of perhaps the most intractable issue his task force will confront. That's why he expects its findings to be "fairly mechanical," having to do with "improving" techniques for intelligence and preemption rather than with revolutionary departures from past practice. He roundly dismisses reports of resort to assassination of known terrorist figures: "We can't do that and we shouldn't. If we did, we'd start unraveling the intelligence community again."

If it is in the nature of things that some shadow of a doubt about the president's health will linger on, it follows that in the nature of politics the public focus will sharpen on an incumbent vice president who is already a prime candidate for the Republican nomination in 1988. The chance encounter last Monday offered no more than a snapshot. But it showed a George Bush both sensible and sensitive enough to carry on business as usual in the absence of any good reason to do otherwise.