Bush Popularity Seen Hinging On Good Times. White House watchers worry the honeymoon could end abruptly at the first sign of crisis. THE FIRST 100 DAYS

IT is the springtime of content for George Bush. As bright red tulips bloom on the White House lawn, the President marks his 100th day in office tomorrow while basking in positive political news. He enjoys a favorability rating of nearly 4 to 1, and is widely admired, especially among Southerners, young people, and men.

Yet the nation's political cognoscenti are mildly uneasy.

They admit that the President does well at times like this, when the weather is fair. But they wonder what will happen when the clouds gather, the storms come, and the rains of recession or international crisis pound on the White House.

Experts concede that the American people are favorably disposed toward Bush. And why not? He has shown himself to be a friendly fellow who plays horseshoes, takes foreign leaders to baseball games, and personally ushers tourists around the White House. Furthermore, the times are prosperous and peaceful.

Republican consultant Edward DeBolt says Bush's current style of governing is fine - as long as there are no major problems. But Mr. DeBolt, like other experts, worries about what lies ahead. He explains:

``Having been familiar with political candidates for a long time, my concern is that he is doing very obviously cosmetic things. The danger is, when anything bad happens, there will be a backlash against the President. People will say, `If he were not spending his time going to ball games and playing horseshoes, we might not be in this mess,''' he says.

DeBolt, who works out of Arlington, Va., adds: ``There are no pictures [on TV] of President Bush working late at night, with his sleeves rolled up - there's no picture of a thinking President. Instead, it's a good-old-boy image.''

Mervin Field, a California pollster, echoes similar thoughts:

``Bush isn't coming across yet as a leader. He doesn't have that special reservoir of goodwill that Ronald Reagan had. ... Bush needs to score successes and be on top of things, and he doesn't seem to have that image now.''

Several analysts suggest that the Exxon oil spill in Prince William Sound, Alaska, was a graphic example of Bush's failure to move quickly and decisively.

Earl Black, a political scientist at the University of South Carolina, notes that Bush ``campaigned as an environmentalist and ... this was his opportunity to move swiftly.'' But he failed. Ten million gallons of oil washed along the Alaska shoreline, while the White House dawdled.

The President ``creates the impression of responding to events, rather than defining his own positions,'' Dr. Black says. ``Over the long haul, this creates the possibility that he may be perceived as too cautious.''

DeBolt agrees. Bush is vulnerable to the charge that he should have acted more forcefully on the Exxon crisis, DeBolt says, and adds:

``Another president, the night it happened, would have brought in the Interior secretary and environmental experts. They would have been called to a midnight meeting. ... He would have immediately dispatched a top person to Alaska, or maybe even have done a personal flyover. ... That would have shown he was paying attention to details. But we don't see that kind of initiative from the White House.''

Analysts say that while Bush remains popular, he should work extra hard to ``put some things into the cash register,'' as DeBolt puts it. As time goes by, presidents accumulate both merits and demerits, and Bush should make sure he remains ahead on points.

Already, Bush is piling up some early demerits, according to analysts. Examples:

A demerit for the trial of Lt. Col. Oliver North, when it was disclosed that Bush apparently knew more about the Iran-contra affair than he admitted.

A demerit for his slow and ineffective response to the Exxon oil spill.

A demerit when gasoline prices skyrocketed on the West Coast following the oil spill.

A demerit when interest rates rose, and housing starts fell.

``These things are like Chinese water torture,'' says DeBolt. ``They are in the public consciousness. ... The effect is cumulative.''

George Grayson, a political scientist at the College of William and Mary, warns that recession, which some economists predict later this year, could seriously hurt Bush's standing. But equally great dangers could be posed by things that Bush cannot see coming.

Dr. Grayson predicts, for example, that bills could soon come due on the environment, maintenance of military equipment, and nuclear weapons plants.

``We have toxic waste to deal with, nuclear plants that are no longer serviceable, and enormous stocks of military weaponry that in some cases go back to World War II. ... These problems are scary, for we cannot predict where they will arise. ... We do not know, for example, what sort of `No. 10 green yuk' has been buried on private or public land, and there is where the problems can arise.''

Pollster Field says that Bush could easily fall behind public opinion on issues like the environment. He notes that in the Los Angeles basin, people previously did not connect environmental problems with their own lives. There was only detached concern.

That is changing. Environmental problems are fusing with personal life styles. Oil spills mean higher gasoline prices. Pollution means lost income. Toxic waste means higher taxes. Chemical emissions mean dangerous air. If Bush falls behind the public on these issues, he could be hurt.

Such problems, however, seem far away this week in springtime Washington, where most eyes are focused not on the White House, but on Speaker Jim Wright's problems in the House of Representatives.

Thanks to Mr. Wright's woes, the North trial and its potentially embarrassing revelations about Bush were only Page 3 news around the country.

But experts warn: Bush can't always count on something like the Wright affair to bail him out of future trouble.