Bush Tries to Sow Doubts About Rivals : Politics: He seeks to shore up support in trip to California. His advisers resist suggestion they plan to present him as the ‘lesser of three evils.’

WASHINGTON — As President Bush returned to the campaign trail Thursday, flying to California for urgently needed fence-mending, his campaign strategists were increasingly convinced that America’s sour mood could persist into November and leave voters unhappy with Bush on Election Day.

Aides have apparently begun to develop a fallback strategy aimed at securing victory for Bush even if a rebounding economy, the historic nuclear arms cuts agreed to at this week’s summit with Russian President Boris N. Yeltsin, and other gains fail to dispel voters’ dissatisfaction.

The heart of the new strategy, heard in the darker cadences of Bush’s recent political speeches, is a blunt warning that voters unhappy with Bush ought to think twice about the alternatives.

“There’s a flip side to change,” Bush advised Republicans in Harrisburg, Pa. “It’s called trust. Trust to make the right decisions, trust to block the wrong decisions, trust to make the tough call . . . . “

As remains his custom, Bush did not mention his rivals by name. But at a time when his surrogates are questioning the character of Democratic Arkansas Gov. Bill Clinton and undeclared independent Ross Perot, advisers acknowledged that it was hardly coincidental that the President talked about “trust” five times in two sentences.

Echoing that theme, deputy campaign manager Mary Matalin told a group of California reporters that, when voters choose a President, “they want to know that they can trust him, that he’s honest, that he’s steady . . . that he’s not going to run off and do something crazy.”

Robert M. Teeter, chairman of Bush’s reelection campaign, said: “It’s just my gut feeling that when it comes down to a choice between two or three guys, voters are going to be most comfortable with George Bush.”

So far as Bush’s prospects in California are concerned, local Republicans are convinced that some kind of change is badly needed. Advisers made no attempt in advance of the trip to pretend that he could expect a warm welcome.

In closed meetings Thursday and today, Republican political operatives in the state were expected to warn Bush en masse that the state’s prolonged economic difficulties make it “fertile ground for Ross Perot.”

Matalin said flatly: “We really have to start connecting and we’ve not been able to.”

Bush strategists say he can win reelection without California, but they liken the task to “playing to an inside straight.” And they say the state will be a top campaign priority.

As Bush seeks to regain favor in California and around the country, political advisers like Teeter resist the suggestion that their plan is to present Bush as the “lesser of three evils.”

But Teeter said in a lengthy interview that the campaign has begun to adjust to the grim prospect that--come November--most voters may still regard Bush with disapproval and believe that the nation remains on the wrong track.

The acknowledgment marks a sharp revision of what had been the Bush campaign’s reelection doctrine: that the rebounding economy and successes like the arms reduction treaty would send voters’ spirits soaring and lift the President into a second term.

The President’s advisers say he will not abandon the campaign trail refrains that boast of such achievements and cast him as an agent of change. But in urging voters to take a hard look at the opposition, he has begun to adopt what some political experts describe as an incumbent President’s tactic of last resort.

“This is George Bush wearing his Harry Truman hat,” said political scientist Ross Baker of Rutgers University, comparing this year’s White House efforts to Truman’s uphill--but ultimately successful--1948 reelection campaign. Truman stumped the country castigating the “do-nothing Congress,” which was in Republican hands, and suggesting that GOP nominee Thomas E. Dewey would give voters more of the same.

The time-tested tactic, as Baker summed it up, calls for a President to tell voters: “Even with the problems you have, you know who I am and you don’t want to go with brand X.”

While Bush advisers refuse publicly to say so, the strategy is also certain to bring a harsher character to the fall campaign. For one thing, to win, the Bush team must find a way to reverse poll findings that now show more voters holding strongly unfavorable impressions of the President than of either Perot or Clinton.

In interviews, Teeter and other Bush aides say they see no need for now to devote much criticism to Clinton, whose campaign has fallen under the Perot shadow. But Republican Party Chairman Richard N. Bond and other surrogates have already begun to sound a campaign-backed chorus painting Perot as a candidate with an “authoritarian perspective.”

“Sooner or later the symbolism and the euphoria of this larger-than-life protest candidate is going to come down to reality,” Matalin insisted in an interview.

As Bush began his two-day trip through California, aides said he did not intend to dwell either on his opponents or on any single issue. Instead, he was to issue a broad appeal to Californians, fearing that they have yet to hear his pleas for change and reform.

But the subtext of a sharper-edged campaign was becoming increasingly legible. Aides insisted that what voters in the state and elsewhere wanted most to know had to do with the character of the candidate who could soon be “sitting in that office.”

With Bush beginning his first full-fledged campaign trip in months, the unease of the situation appeared to be etched ever more deeply on the face of a President who, confidants say, appears to have lost his self-confidence.

“He used to have an intuitive sense about when things were working,” said one source close to Bush who would speak only on condition of anonymity. “But this is such a strange year that he’s begun to say you can’t be sure of anything.”

Bush seemed more relaxed by Wednesday as he and Yeltsin wrapped up their two-day summit and signed the arms agreement. But he again referred to what he called “the strange year” in which he was enmeshed.

And, after months of assuming that foreign-policy achievements would yield boundless electoral dividends, advisers were beginning to acknowledge even as Bush spoke that they had come to question that orthodoxy.

With the passing of the Cold War, one senior Bush campaign aide said, the political benefit of arms agreements may simply have been devalued.

“These are not the first things on people’s minds,” another official said, “because the threat has just been so much diminished.”