DES MOINES, MAY 31 -- The clue to how nicely Vice President Bush thinks his candidacy is going these days was buried in a bland speech he gave here this weekend to a big gathering of GOP foot soldiers from the Midwest.

Applause lines? Policy proposals? Stirring visions? Not from the GOP front-runner. Bush was all busines, which is to say, safe, predictable and a tad boring.

But like Sherlock Holmes' dog that did not bark, the speech spoke volumes silently. It told of the luxuries -- real and false -- of being an institutional front-runner a year before a presidential convention.

"We're moving the ball on the ground just fine. Unless they make us put it in the air, why do it?" asked Rich Galen, a consultant to Bush's political action committee. "Every time you take a position, you know you'll make someone angry."

This "why-take-risks" attitude reflects a common belief in the Bush high command that after a lousy start, 1987 has stabilized nicely. Contributions are pouring in and being stockpiled; endorsements are mounting; Bush's dip in the polls proved short-lived. Most important, the Iran-contra affair, source of the woes of a few months ago, seems to have lost its grip on the public imagination.

"I haven't gotten a single letter about the hearings since they began," said Rep. Steven Gunderson (R-Wis.), a probable supporter of Sen. Robert J. Dole (R-Kan.). "That's got to be good news for the vice president."

Most Bush supporters now assume that the hearings will bring no more major revelations, giving their campaign leeway to follow the classic front-runner's gambit of delaying the head-to-head contest.

Bush staked out his now-familiar "I'm-vice-president-and-you're-not" posture toward the rest of the GOP field here at the Midwest Republican Leadership Conference.

He requested, and received, separate billing in a Saturday luncheon speech so as not to compete with the others in a panel presentation.

They complained. Former Delaware governor Pierre S. (Pete) du Pont IV accused Bush of living in a "cocoon."

"We begin to get the feeling he {Bush} is afraid to get on the same platform with us," said evangelist Marion G. (Pat) Robertson.

There will be plenty of time after he formally declares his candidacy this fall to mix it up, Bush aides say.

Until then, there is money to be counted. Bush has raised nearly $6.5 million since the beginning of this year, close to double what his campaign had projected and more than three times the hauls of his two principal fund-raising rivals, Rep. Jack Kemp (R-N.Y.) and Dole.

Better still, the campaign has been able to salt away $3 million, and political director Rich Bond now projects that by next January, when the first installment of federal matching funds comes in, it will have at least $10 million.

By contrast, Dole is spending money nearly as fast as he raises it, and Kemp, forced to rely heavily on high-cost direct mail, has been running in and out of the red.

The danger in all this good news is that great enemy of all front-runners: false security.

One peril remains especially vivid for Bush -- the absence of a message. That is an old bugaboo for him. After he catapulted to national prominence in 1980, following an upset win in the Iowa caucuses, instead of talking about ideas, Bush talked about momentum. By so doing, he squandered his.

This year's leisurely development of a message is in part a tacit realization of the difficulty of crafting a "things have never been better and I'm the only one who can clean up this mess" theme, as Democratic National Committee Chairman Paul G. Kirk Jr. has characterized the challenge facing Bush.

As long as that hangs over Bush, many GOP rivals will view him as a sitting duck. "It just seems to me that if he loses one of the first two {primaries, Iowa or New Hampshire}, he's a goner," said Don Totten, Cook County (Ill.) GOP chairman and a Kemp supporter.

New Hampshire was not kind to Bush in 1980, but he is hoping the support of Gov. John H. Sununu and his no-new-taxes stance will steady his position.

In Iowa, where the presidential selection process begins Feb. 8, things have brightened for Bush.

Bush went into a slide last year. By February, he trailed Dole 33 percent to 28 percent in the Des Moines Register's poll.

But after several well-publicized visits to the state, Bush jumped ahead of Dole in a late April poll.

"For the moment, George Bush is clearly the front-runner in Iowa," said Steve Roberts, a former GOP state chairman.

Roberts, Dole's Iowa's cochairman, said Bush has benefited from a slight improvement in the farm crisis. "There is less anti-Reagan feeling, and that helps him. Also the Iran arms sales thing is not big news out here," he said.

Top Iowa Republicans agreed that the campaign of Kemp has had trouble getting off the ground. "He's too ideological. People don't understand the gold standard and a lot of the other things he talks about," said Sen. Charles E. Grassley (R-Iowa).

Kemp has reshuffled his Iowa staff and hopes to show movement soon. But Dole, who finished eighth in a seven-man GOP field (behind "undecided" and six candidates) in the 1980 Iowa caucuses, this year is the one considered best-positioned to upset Bush.

Dole's edge here is that he is a fellow Midwesterner. "There's nothing very complicated about Bob Dole," he told the GOP conference today. "I came from a little town called Russell, Kan . . . . My mother sold sewing machines. My father had a cream and eggs station and a grain elevator. We all worked."

Dole said he was "a stronger person" because of his experience of "growing up in a small town where we understood the problems of everyone, where we took care of everyone, where we didn't know what discrimination was."

Former senator Paul Laxalt of Nevada chided other GOP candidates today for attacking Bush.

"Let's observe very closely the 11th Commandment . . . . 'Thou shalt not speak ill of another Republican,' " Laxalt said.