PANAMA CITY -- After trying for the past three years to strengthen his grip on power by delaying Panama's return to civilian democracy, top military commander Gen. Manuel Antonio Noriega now appears to have seriously weakened his position by failing to respond to public demands to get the Army out of politics.

Last week, for the first time since he became Panamanian Defense Forces commander-in-chief in 1983, Noriega was on the defensive, parrying opposition protests with uncharacteristic recklessness.

He tried to mobilize support among leftists by accusing American conservatives of fomenting unrest to thwart the process of turning over control of the Panama Canal to the Panamanian government by the year 2000. But the charge drew only lukewarm support and alienated him from Panama's most influential business and Roman Catholic Church leaders.

After two weeks of protests and growing public resentment over his purported role in rigging the 1984 presidential vote, Noriega faces an uphill battle to stay in power until the next presidential elections in May 1989, foreign diplomats and military observers said.

"There will be no putting Humpty Dumpty together again," said one foreign military observer familiar with the Panamanian military.

In the recent two-week upheaval, many more Panamanians turned against the government that Noriega controls than in the riots of 1984 and 1985. Until now, the opposition had been limited mostly to right-of-center, middle-class political parties sarcastically labeled rabiblancos, or "white tails," by the largely black working poor.

But even columnist Demetrio Olaciregui, one of Noriega's most articulate supporters, noted: "What we saw was an outbreak of popular discontent, not because it was summoned by the rightist opposition, but because it's there -- latent. . . . The scorecard did not come out well for the Defense Forces."

"This crisis really shook the country," said Catholic Archbishop Marcos Gregorio McGrath, who has spoken with caution to preserve his neutrality during the turmoil. But he warned: "If we simply close our eyes, we're going to have deeper and deeper rifts."

The roots of the turmoil stretch back to 1979 when the widely admired nationalist leader Gen. Omar Torrijos announced a Defense Forces "retreat" to make way for an elected civilian president. The 20,000-troop Defense Forces had seized power in a 1968 coup. Torrijos' popularity surged when he signed the 1977 treaties with Washington to turn over the canal to Panama.

Torrijos was killed in a 1981 plane crash. But the return to democracy inched forward until the May 1984 vote. Noriega is believed to have rigged it against veteran politician Arnulfo Arias, who would have named a new commander-in-chief.

Then, in September 1985, Noriega ousted the president he had installed, Nicolas Ardito Barletta, reportedly for seeking an investigation of the murder of Hugo Spadafora, a popular figure who spoke out against Noriega.

Retired colonel Roberto Diaz Herrera, Noriega's chief-of-staff until he was forcibly retired June 1, has admitted that he bribed polling place magistrates to ensure the victory of Noriega's candidate. The accusations, publicized by Diaz, that Noriega was directly involved in murder and corruption cases ignited the riots that began June 9.

In a communique last week McGrath and the 10 other members of the Catholic Bishops Conference called for immediate measures to establish "a real autonomy of civilian power and the progressive return of the Defense Forces to their appropriate tasks."

"In any government that has been in power for an awfully long time, problems of graft develop -- like Tammany Hall -- which have to be cleared up," McGrath observed. "The fact that the Defense Forces' retreat hasn't continued hampers all the branches of government."

Noriega remained silent about the church's statement. But a government censor removed the communique from the Sunday edition of the opposition daily La Prensa, the first issue of the paper to be published since censorship was imposed June 11. A radio station Noriega controls called the Panamanian archbishop a "boozer" and a "gringo," a slang word for American.

Noriega also encouraged the National Assembly to level charges that nine prominent Panamanian businessmen and politicians had conspired with U.S. conservatives to overthrow President Eric Arturo Delvalle.

All those mentioned privately denied any plot ever existed. Three of those named -- lawyer Roberto Aleman, financier Federico Humbert and banker Roberto Motta -- went public with their outrage, arguing that they were not even involved in any anti-Noriega protests. Aleman, who served in the 1960s as ambassador to Washington, was on business in the United States when he was said to be hatching the plot.

"They think I'm 007, playing golf in Washington and leading a revolution in Panama at the same time," said Aleman, a government supporter until this incident.

The attack on some of Panama's most prosperous executives cemented the views of many in the highest business echelons who long had cooperated with Noriega but turned away from him with the recent disturbances.

"This situation really touched our soul. Our dignity was hurt," said one prominent Panamanian entrepreneur who did not want his name published. Many other business leaders said privately that Noriega should step down.

The most conspicuous defector was wealthy investor Gabriel Lewis, who fled Panama June 13 after he had tried unsuccessfully to mediate between Noriega and the opposition. Congressional sources in Washington said Lewis went to many policy makers there last week with the message that Noriega should be replaced.

Noriega is expected to turn now for support to his leftist political forces, primarily the Democratic Revolutionary Party, which was created by Torrijos in 1979 as a party supporting the military.

Democratic Revolutionary Party followers portrayed the crisis as a clash between poor working blacks and the "white tails." They accused the middle-class opposition of pushing to regain the power they lost two decades ago to Torrijos and his supporters among the poor.

But party leaders made it clear that their backing this time is going to cost the government money. In the tangled Panama City slum of San Miguelito, rioting erupted earlier this month for the first time in years. Worried Democratic Revolutionary Party leaders who run the town hall there said bluntly they are demanding $1.3 million public funds immediately to create jobs and put up housing.

The party's strong-arm, ward-heeling style can be effective. The party summoned soldiers to collect the garbage last week in San Miguelito instead of the regular civilian crews, to renew the Defense Forces' bonds with the slum dwellers.

But the goverment will face an economic bind when it tries to divide Panama's tight budget among Noriega's leftist political ranks. With a foreign debt of at least $4.5 billion, Panama must slash its inflated public spending to qualify this year for fresh international bail-out loans. Hardest hit will be the social security and public urban job programs that the party is pressing.

Reuter reported the following from Panama City:

Nicaraguan President Daniel Ortega will meet Wednesday with Panamanian President Delvalle to discuss faltering Central American peace efforts, government newspapers and the Nicaraguan Embassy announced today.