Democratic presidential nominee Walter F. Mondale's campaign has dropped its "Reagan deficits" attack strategy, shifted to a litany of provocative Democratic themes, and shuffled its message-making management in a last-ditch effort to resurrect its failing drive for the presidency.

In his speeches and mainly in a new round of television ads, Mondale has started to talk about issues Democrats deem worth fighting for: President Reagan's ties to right-wing evangelical leaders, his policies in Central America, his hopes of stocking the Supreme Court with anti-abortion conservatives, his opposition to the Equal Rights Amendment.

Mondale campaign manager Robert G. Beckel has assumed expanded duties, moving into the making of television commercials where campaign adviser Richard C. Leone once presided alone.

Late last week, Beckel, working with media specialist Roy Spence, produced his first Mondale television commercial of the fall. It is a comprehensive statement of the the new Mondale catechism: an ad that lashes at Reagan's efforts to bring right-wing evangelical leaders into his campaign and policy-making efforts.

The ad opens with a man and a woman reading an invitation: "Ronald Reagan and Rev. Jerry Falwell cordially invite you to join their party on Nov. 6." The message continues: "Here's all you have to believe in. The secret war in Central America. All new Supreme Court justices must rule abortion as a crime even in the case of rape or incest. No Equal Rights Amendment for women. No mutually verifiable nuclear freeze."

A picture of Reagan and Falwell follows, along with a final message: "Think about the people who have taken over the Republican Party. They want their new platform to be your new Constitution. Think about that."

The Mondale strategy, now -- solidifying the Democratic base -- has its roots in the pleadings of some senior advisers inside the campaign and many of the party elders outside who have been jarred by the prospect of a Mondale defeat so large that he could take much of his party down with him.

The new strategy is aimed at recapturing Democratic voters -- older voters and blue-collar voters -- who seemingly should be Mondale's by now but who are telling pollsters they are for Reagan.

The changes did not come tranquilly, according to some high-level campaign advisers. "The era of the deficit is dead, but it did not die easily," said one insider. "There was a struggle within," said another.

The new strategy was forged in an internal battle that involved most of Mondale's senior advisers and led to a pivotal reshaping of Mondale's Sept. 25 speech at George Washington University. The shift in ad strategy followed.

Leone, Mondale's senior message strategist, had scheduled the speech as a foreign policy address, designed to follow Reagan's U.N. address of the day before. It wound up as a sweeping assault on Reagan's policies and practices -- foreign and domestic, moral and political -- with Mondale declaring at one point, "I would rather lose a race about decency than win one about self-interest."

While Leone reportedly fought for the strong foreign policy focus, other staff advisers, including Beckel, Paul Tully, John Reilly and Tom Donilon, pressed for the more sweeping and politically evocative Mondale address as it was finally drafted by speechwriter Martin Kaplan.

Public opinion analyst Patrick Caddell, who once was on sour terms with Mondale and his loyalists, played a significant role in this change even while remaining officially outside the campaign structure, according to a number of senior Mondale staff members.

He has done a national poll for James A. Johnson, Mondale's campaign chairman, and had been advising Johnson and Beckel that the Democratic nominee faced the prospect not only of a landslide defeat, but one that could send many traditionally Democratic voters into the Republican camp if he did not hammer in basic Democratic beliefs worth fighting for.

Caddell maintained that the Mondale campaign had been wrong to make its case against the Reagan administration's budget deficits as an argument of economics and taxes; he argued that the president was building his recovery by mortgaging the future of the next generation.

Johnson, in an interview, spoke of Caddell's role. He said the pollster's advice in the wake of the Waterbury, Conn., speech in which Reagan tried to wrap himself in John F. Kennedy's aura led to Mondale's radio address invoking the litany of Democratic beliefs.

Johnson also confirmed Beckel's enhanced role. Johnson said the strategy shifted after the September polls showed Mondale losing by "large proportions."

Earlier, Leone had radiated confidence that the all-out assault on the dangers of the deficit would produce political profits. "We'll make Ronald Reagan eat his deficit," Leone said in August.

But the anti-deficit barrage consisted of immutable speeches, indecipherable charts, incomprehensible gimmicks and inconsistent ads.

Leone formed a consortium of commercial specialists, but that partnership has fractured. Spence has produced virtually all of the Mondale ads that have aired, taking his directions from Leone. The other best-known member of the consortium, political consultant David Sawyer of New York, has produced only one, early ad.

Sawyer is said to have prepared three ads attacking Reagan as trying to sidestep the blame for ill-conceived policies and lax security that led to large numbers of American deaths in Lebanon. But the ads never ran.

"It's like the 'Night of the Living Dead,' " said one Mondale adviser. "It's like they came in and took us over. Everything we do is so brilliant -- for Reagan."