The Democratic Party, although distracted by the resignation of Secretary of State Alexander M. Haig Jr., today turned its oratorical guns on "the national disgrace" of the Reagan administration's domestic policy.

While delegates to the mid-term national party conference buzzed at news of the surprise upheaval in the State Department, relayed to them by party chairman Charles T. Manatt, half a dozen 1984 presidential hopefuls took turns beating up on the vulnerable-looking president.

None outdid House Speaker Thomas P. (Tip) O'Neill Jr. (Mass.), who said in his keynote talk that "what the Republicans called a 'New Beginning' has turned into a national disgrace," marked by record unemployment, huge budget deficits and a "tearing of the social safety net to shreds."

Former vice president Walter F. Mondale clearly won the day's oratorical honors with a tough, emotional attack on Reaganomics. The speech has been rehearsed in dozens of states where he has campaigned this year. His stiffest competition is due when Sen. Edward M. Kennedy of Massachusetts addresses the delegates Sunday.

News of Haig's resignation came too late to figure in today's speeches, but it may affect consideration Saturday of a policy statement on the Middle East that would put the party on record for "every effort to reinstate Lebanese sovereignty and Israeli security," following an Israeli invasion it describes as having broken "the vicious cycle of violence" in the region.

The resolution, written by Washington political consultant Mark Siegel, says, "International terrorism has been dealt a severe blow, and Soviet influence has been reduced."

Party officials predicted that it would be approved, but there were expressions of misgiving from some delegates about what they took as a blank-check endorsement of the Israeli action.

Some, such as Manatt, denied reports that they had expressed approval of the resolution, saying they were only voicing support of Israel in general and acknowledging that such a resolution would come up.

The Democrats, most of them veterans of the 1970s political wars, gathered in a guardedly optimistic mood, believing that Reagan's economic policies have given them a winning issue for the 1982 campaign. After the speeches, the delegates spent the evening touring receptions for the 1984 presidential hopefuls.

Speaking under a banner that read, "Democrats. With Fairness to All," O'Neill began a long afternoon of oratory by jibing that Republicans could not go back to Detroit, where they held their 1980 convention, because "they have not kept their promises to the citizens of Detroit, the citizens of Michigan or the citizens of this country."

The House speaker, favorite target of Republican attacks for the last two years, seemed to welcome the chance to return a dose of the same medicine. Often accused of favoring "tax and spend" policies, O'Neill said the GOP's alternative was no more than "borrow and buy, borrow and buy."

"Ronald Reagan is the biggest budget-buster in history," he declared with relish. "It doesn't make sense to do what the Republicans are doing and cut tax revenues by $750 billion at the same time we are spending $1.6 trillion on defense."

Californian Alan Cranston won the leadoff position among the presidential hopefuls by virtue of his position as deputy Senate Democratic leader and drew a laugh by saying he wanted to "dispel any rumors of rivalry among the Democrats. In the spirit of unity, I pledge my wholehearted support to Ted Kennedy--in 1982."

Turning serious, Cranston assailed Reagan as "oblivious to some of our greatest national problems, indifferent to others . . . superficial and simplistic."

Cranston devoted most of his speech to the nuclear arms issue, saying "neither Ronald Reagan nor the people who surround him have the commitment or the capacity to stop the nuclear nightmare."

In earnest tones that did not entirely still the buzz of conversation on the floor, Cranston said the United States must make an "all-out effort, the like of which we've never seen, to negotiate a fair and verifiable nuclear freeze.

"We must banish these weapons from the face of the Earth," he declared.

The delegates were encouraged to blow off steam in a musically orchestrated demonstration of continued Democratic support for the about-to-expire drive to ratify the Equal Rights Amendment.

With band blaring and banners waving for the first time in the day, a group of women officeholders and candidates was joined on the podium by the presidential hopefuls and provided a pageant of party unity in ample time for inclusion on evening television news shows.

That was followed by a pitch from Rep. Claude Pepper (Fla.), 81, the oldest man in the House, on the Social Security issue that Democrats consider one of their strongest weapons for the fall campaign. Then it was time for presidential hopefuls to parade their stuff again.

Mondale, who has been on the road almost nonstop in recent months, drew a geographical portrait of America in the Reagan era.

"Whether they are teachers in Birmingham, students in San Diego, woodworkers in Portland or auto workers in Detroit, all across this land, good, solid, decent Americans are suffering through no fault of their own," he said.

Then, as if he were already the 1984 nominee, Mondale addressed Reagan directly: "Mr. President, we are not a lazy people. We don't want welfare. Americans want to work. We want to stand on our own two feet. And you should stop blaming people and start helping Americans get back to work."

Mondale also personalized the nuclear arms issue against Reagan by charging that the president "for 20 years has opposed every step toward arms control by every president of both political parties."

He echoed Cranston's endorsement of the nuclear freeze but concentrated his fire on the domestic scene, which he said had been devastated by an economic policy "not moderate or conservative but radical and wrong."

That shot and others drew much more enthusiastic bursts of applause than Cranston had achieved, certifying Mondale's position as the real rival to Kennedy in the delegates' favor.

But South Carolina Sen. Ernest F. Hollings, who followed him, provided a contrast, if not a challenge. In unusually blunt language, he suggested that "the Achilles heel of the Democratic Party is managing the economy" and that "Democrats in Washington discredit the party by failing to make an effort to control the budget deficit."

Hollings, ranking Democrat on the Budget Committee, said his colleagues "hid behind the issue of Social Security, which Democrats couldn't lose if they had to, and missed the chance of exposing Reaganomics."

Implying that the party still suffers from the 1980 perception that Democrats were too subservient to single-interest groups to handle the nation's affairs, Hollings bluntly declared, "On the all-important issue of the economy, the people still shy from us." His speech predictably drew a cool response from delegates.

Sens. Gary Hart of Colorado and John Glenn of Ohio drew the unenviable assignment of concluding the verbal marathon. Hart has pitched his campaign on a detailed presentation of new policy approaches to the economy and national defense, while Glenn has made himself a spokesman on military and technology issues.

But both decided to try for applause lines today--Hart in his first major speech to a Democratic gathering and Glenn in an effort to erase the memory of his flop as co-keynote speaker of the 1976 convention.

"It doesn't matter if Ronald Reagan is the greatest communicator in history if all he has to communicate is division and despair and depression," Hart declared.

Then, picking up the theme of his first campaign for the Senate in 1974, Hart said that because the Republicans have failed, "now it's our turn."

Turning his complex proposals for overhaul of the tax laws into a simple slogan, Hart said, "We must lead the tax revolution of the 80s--a true Jeffersonian rebellion against Trojan-horse, trickle-down tax cuts for the rich--a revolution that will finally lead to tax justice."

Then, hitting another of his pet subjects a glancing blow, the young Coloradan urged Democrats to support "a defense that is the most effective and not merely the most expensive."

Hart held the audience's attention although he spoke well into the cocktail hour, and got some, but not a lot, of applause.

Not to be outdone, Glenn closed the parade by called the Reagan record "a string of failed policies and a trail of broken promises." As if to answer complaints that he was a dull speaker, the former astronaut delivered a string of applause lines, such as:

"If this administration actually believes that throwing people out of work is part of the cure, then we'll be happy to give them a dose of their own medicine in 1984."

And: "The president says appointing Sandra O'Connor to the Supreme Court proves his commitment to equal rights for women. But we Democrats say there is a huge difference between making one woman a justice and bringing justice to American women."

And: "As for granting tax exemptions to so-called Christian schools that try to justify racism on religious grounds, we Democrats say it's high time this administration stopped confusing the epistles of the New Testament with the apostles of the New Right."

Glenn's applause lines received applause, but his very soft-voiced delivery permitted a steady rise in the level of conversation on the floor, and the hall was emptying before he finished.