"My heart was pounding so fast, I thought the microphone would pick it up," said Sen. Christopher J. Dodd (D-Conn.), recalling his televised response for the Democratic Party to President Reagan's April 27 congressional address on Central America.

In an emotional speech, Dodd charged that increased military aid sought by Reagan would guarantee only "greater violence . . . greater bloodshed" in the region.

At a breakfast with reporters 36 hours later, House Majority Leader James C. Wright Jr. (D-Tex.) also struggled to control his emotions. He assailed the "hyperbole" and "florid rhetoric" of Dodd's speech, adding, "It is a dangerous exercise for people to club the president on a delicate matter of foreign policy."

While Republicans watched with undisguised satisfaction, the Democrats suddenly plunged their party into its most divisive internal foreign policy debate of the past three years.

Analyses by political columnists suggested that the Democrats had played into Reagan's hands by setting themselves up as the fall guys for a potential "Who lost El Salvador?" campaign.

Reagan repeatedly raked the Democrats, accusing them of being "very irresponsible" on a party-line vote in the House Intelligence Committee aimed at stopping U.S. covert aid to guerrillas fighting the leftist government in Nicaragua.

By this weekend, emotions had cooled somewhat, but the policy disagreements were just as large. Wright said he thinks there "still is a way" to avoid a Democratic split that he conceded "has the potential" of rekindling the antagonisms of the Vietnam war period.

"It's possible" for the Democrats to be mousetrapped, he said in an interview, "if we follow the lead of those who would totally disavow" the "democratically elected government" of El Salvador, which is fighting leftist rebels who Reagan says are supported by Nicaragua.

"That would be as destructive as the McGovern view of Vietnam," Wright said, referring to the 1972 antiwar presidential campaign of then-Sen. George McGovern (D-S.D.). "But we haven't done that yet."

Dodd, in a separate interview, said he knew in advance that "there were a lot of Democrats who agree with the president on this." But, he insisted, "it was no mistake for the Democrats and no mistake for me" to challenge Reagan's contention that the source of trouble in Central America is external communist-backed subversion.

As for fears that Reagan can blame Democrats for tying his hands in Central America, Dodd said "there's not much danger" of that happening. If Salvadoran rebels win the military struggle, Dodd said, "It is on Reagan's watch. He can't blame it on the junior member of the Foreign Relations Committee Dodd --not with any credibility."

Senior Democrats, including some who differ with Dodd and others who share his view, tried to argue that if anyone has breached bipartisanship on this issue, it is Reagan and not his critics.

Rep. Dante B. Fascell (D-Fla.), ranking member of the Foreign Affairs Committee, said the president was "not willing to give us a voice in the formulation of policy; he just wants acquiescence in its implementation. And that produces confrontation."

Wright echoed that complaint, as did such moderate Democrats as Reps. Lee H. Hamilton (Ind.) and Norman Y. Mineta (Calif.).

For all of their efforts to shift political responsibility to the president, many Democrats acknowledged that the Central American policy debate had revealed deep divisions in their party on the limits and uses of U.S. power.

Those divisions, many said, stem from generational and geographical differences as much as from ideological and strategic disagreements. Therefore, they said, they may be all the more difficult to bridge.

That realization has ended a brief euphoria in which Democrats allowed themselves to believe that the bitter debate starting with the Vietnam war escalation in the mid-1960s and continuing almost unabated through the defense-budget and arms-control controversies of the Carter years was finally behind them.

At the Democratic mini-convention in Philadelphia last June, representatives of all of the potential presidential candidates and all of the major constituency and ideological groups agreed to a foreign policy-national security program portraying what Sen. Paul E. Tsongas (Mass.), the panel chairman, called "a picture of Democratic unity."

"For the first time in a long time," wrote Ben Wattenberg, a hawkish activist and battle-scarred veteran of debates on Vietnam, defense and arms control, "the Democratic Party has taken a big step toward a tough, intelligent statement about defense and foreign policy."

Last week, the same Wattenberg assailed Dodd's official Democratic Party response as "demagogic" and warned that unless the Democrats "extend substantial cooperation to Reagan in Central America . . . they will risk losing the 1984 election to a Ronald Reagan who will charge all across the nation denouncing them as spineless."

That fear is widespread among congressional Democrats, even though public opinion polls currently suggest that Reagan's expanded American role in Central America is unpopular.

A Los Angeles Times poll taken in early April found that less than one-third of those interviewed believed that U.S. "involvement in El Salvador" was either morally justified, vital to national defense or likely to end in victory.

A Gallup Poll taken for Newsweek magazine after Reagan's nationally televised address on the issue found slightly more people saying that the United States should "stay completely out" of El Salvador than favoring any "help to the current government" there.

Nonetheless, many Democrats--out of either deference to the president or fear of the fickleness of public opinion--would prefer to avoid an open confrontation with his policies.

"I think the Dodd analysis is shared by most Democrats," one knowledgeable leadership aide said, "but I also think most Democrats would just as soon not get involved, not get committed. The last question of the Reagan speech hangs heavy over their heads."

Reagan ended his address by asking, "Who among us would wish to bear responsibility for failing to meet our shared obligation?" That was a signal that if things go badly, he is ready to point the finger of blame at Congress.

Rep. Clarence D. Long (D-Md.), chairman of the Appropriations foreign operations subcommittee, was cited by several other members as typical of those who are looking for cover on the issue.

On April 26, Long engineered a squeaky 7-to-5 vote, virtually on party lines, giving the administration $30 million of the $60 million in emergency aid it sought for El Salvador, after Secretary of State George P. Shultz agreed to conditions, including appointment of a special envoy for Central American negotiations.

As a result of that action, Long said Friday, "I think we're in a good position to prevent the president from blaming us for whatever happens." Saying the mail he has received on the issue has been "pretty small," Long said that "the net effect has been to blunt the attack on the Democrats."

Democratic congressional leadership aides said that it was suggested to Dodd that his response emphasize Congress' past support of aid to El Salvador and say that Reagan was out of step in attempting to circumvent the strong bipartisan vote last year against covert efforts aimed at overthrowing the Sandinista government in Nicaragua.

But Dodd rejected what he called that "legalistic approach" and framed his reply as a broad and emotional indictment of those who would "loose the dogs of war" on a region whose real problems, he said, are economic and social, not ideological.

Dodd cited his experience as a Peace Corps volunteer in Latin America, and many congressional Democrats who share his views also are products of the 1960s.

"Of course, we see an analogy to Vietnam," said freshman Rep. Robert G. Torricelli (D-N.J.), a Foreign Affairs Committee member. "The El Salvador debate is like walking through our college years again--except now we're involved."

Another member, requesting anonymity, said, "The Wrights and the Longs and that generation may be haunted by the 'Who lost China?' question, but the younger ones are thinking about Vietnam."

In addition to the generational difference, congressional Democrats also confront a sharp geographical split. "Dodd and Wright," Sen. Daniel Patrick Moynihan (D-N.Y.) said, "reflect the difference in perspective of Hartford and Fort Worth."

Generally speaking, Democrats from the South and Southwest are more inclined to back the president, in part because of their region's closer economic links to Latin America and in part because their constituents fear that new refugees from communism would, like the Cubans, settle in their cities.

Fascell, Hamilton and Wright are still seeking formulas for funneling additional aid to El Salvador, without seeming to give Reagan a complete green light for his Latin American policy.

But Fascell conceded, "When you try to find a middle ground, you end up being criticized by both sides. There's no question this is divisive."