Minnesota's Democratic-Farmer-Labor Party - the party that nurtured Hubert H. Humphrey, Walter F Mondale and a national tradition of liberal politics - is facing its greatest internal crisis of the past decade in Tuesday's primary election.

Three days ago, the DFL executive committee voted to mortgage the party headquarters building to finance a massive telephone appeal to the party faithful to support the endorsed candidates in Tuesday's voting.

Two days ago, 17 of the party's leaders - some of them veterans with Humphrey, of its founding three decades ago - held a joint press conference to denounce a longtime comrade-in-arms as "the most scary" threat to its traditions to appear on the scene in years.

Yesterday, Mondale himself went home to add his voice to the chorus of pleas for DFL voters to back the endorsed candidates for the two Senate seats vacated by Humphrey's death and Mondale's elevation to the vice presidency.

"If we just had to take the hammering from the other side," said Gov. Rudy Perpich, the leader of the DFL state ticket, "we could handle that. But we're getting hammered from within."

The most ominous pounding is that which Minneapolis businessman Robert F. Short, a longtime Humphrey ally and fund-raiser, is administering to Rep. Donald M. Fraser, the liberal legislator who is the convention-endorsed candidate for the remaining four years of Humphrey's term.

Short is challenging more than Fraser in his unprecedentedly expensive $800,000 primary campaign, financed largely by his own personal loans. He is also challenging liberal policy the DFL and its spokesmen have carried to the nation for 30 years by blaming the "Frasers of this Congress" for runaway in flation and proposing nothing less than a $100 billion cut in federal spending.

In attempting to fulfill his long-denied desire for public office, Short has allied himself with strong anti-abortion, gun-owner and sportsmen's groups opposed to Fraser's stands on emotional life-style and enviromental issues. He has also bid openly for Republican cross-over votes.

It is these factors - as much as the threat to the party-endorsement system - that caused such veteran DFL leaders as former ambassador Eugenie Anderson to label Short "the most scary" candidate.

But Fraser is not the only one with problems Tuesday. Sen. Wendell R. Anderson, who resigned as governor last year to allow Perpich to appoint him to the Mondale seat, has not yet been able to quiet the public outcry about that political maneuver. He is opposed in the primary by John S. Connolly of St. Paul, a Minnesota Mining and Manufacturing heir who has spent about $60,000 of his own money in hopes of exploiting the anti-Anderson sentiment.

And awaiting the bloodied winners of Tuesday's primary voting is a newly revived "Independent Republican" party, mounting a well-financed effort to capture both Senate seats and the governorship as well.

The Republicans have contests of their own which, in nomal times, might attract some interest. Malcolm Moos, former president of the University of Minnesota and an Eisenhower White House aide, is challenging David Durenberger, the attractive young lawyer who is the endorsed candidate for the Humphrey seat.

Perennial candidate Harold Stassen, a onetime Minnesota governor, is opposing Republican National Committeeman Rudy Boschwitz, the flamboyant president of a big plywood company and the endorsed candidate for nomination to the seat Mondale once held.

Rep. Albert H. Quie, leaving the House after 20 years to seek the governorship, has nominal opposition in the GOP race to challenge Perpich.

But this is not a normal year, and the focus - and fireworks - are all inside the DFL, which has dominated state politics and been a major influence on the national scene since Humphrey used it as the vehicle to move from the Minneapolis mayoralty to Washington exactly 30 years ago.

Since then, the party has become a major source of national leadership and programs - providing presidential candidates like Humphrey, Mondale and Eugene J. McCarthy, Cabinet members like Orville Freeman and Bob Bergland, and economic advsiers like Walter Heller.

But the coalition has never been easy to maintain. Drawing from such diverse strands as rural populism, the radical unionism of the Iron Range, the more conventional liberalism of the universities and the Catholic workers' movement, the DFL has been an uneasy alliance of fractious religious, philosophical and political groups.

Humphrey's death has removed the emotional glue-and the political leadership - that held the internal antagonisms at bay. Says Durenberger, a Republican who married a former DFL worker and counts many DFL leaders among his friends: "You just cannot overestimate what they lost when Humphrey was buried."

Even Humphrey's final months, as cancer weakened his grip, the unraveling began. Anderson's haste in grabbing the Mondale Senate seat aggravated a latent resentment among local party and elected officials, who complained that the onetime hockey star had become as "imperial governor."

Fraser, a 16-year House veteran whose low-key style masks a healthy ambition of his own, began testing the waters for a possible challenge to Anderson's election. But when Humphrey's illness made it obvious there would be two seats open this year, Fraser switched his attention to that race. He organized so well in the precinct caucuses that he nudged Muriel Humphrey, appointed by Perpich to fill her husband's seat, into a decision that she would not run for the balance of the term.

As both Anderson and Fraser maneuvered, tensions between their supporters increased, and single-interest groups, which have played an increasing role inside the DFL, began to choose up sides.

Fraser, a former chairman of the House Democratic Study Group and Americans for Democratic Action, drew the fervent support of university liberals, supporters of abortion rights, advocates of gun control, and environmentalists who wanted to bar motorboats from the entire Boundary Waters Canoe Area in northeastern Minnesota.

Anderson, moving the other way, opposed federally financed abortions, backed tuition tax credits for private schools and sought a compromise to allow some use of power boats in the recreation area.

Even though the two men agreed on most other issues and backed each other for endorsement at the state convention as a matter of mutual political interest, one DFL leader says that, "Of the 1,200 delegates, there probably weren't more than 200 who voted for both Don and Wendy, and not more than a dozen who liked doing it."

Yet they had the most practical reasons for working together, in the face of a growing Republican threat. The Minnesota Poll of the Minneapolis Tribune showed that Anderson, dogged by the self-appointment issue, had slipped 23 points behind Boschwitz. Perpich had lost his early lead in the governor's race and was running no better than even with Quie. And Fraser's margin over the lesser-known Durenberger had dropped to 18 points.

Instead of being able to concentrate on that Republican challenge, both Anderson and Fraser have been forced into costly and nerve-wracking primaries.

Anderson's foe, Connolly, is a St. Paul lawyer, previously known only as the leader of the McCarthy forces in the 1968 McCarthy-Humphrey struggle. He has paid for an advertising campaign aimed mainly at telling the anti-Anderson voters they have an alternative.

Short, on the other hand, has dropped about $700,000 of his own self-made trucking-hotel-baseball-hotel fortune into an all-out assault on Fraser and the kind of liberalism he represents.

Now 60, Short has been waiting since 7352 for a DFL endorsement for public office. He has joined in past rebellions - in the 7356 presidential primary and the 7366 gubernatorial fight - but mostly he has provided hotel rooms for party functions and helped pay the party's bills, as he did as Humphrey's campaign treasurer in 7362. But, time and again, the DFL has spurned him for endorsement.

This year's assault is seen by many as Short's full-voiced scream of protest against all the liberals in the party who have taken his money and blunted his ambitions for all these years.

In interviews, he assails Fraser bitterly as an "intellectual who grew up on the University of Minnesota campus" and "knows nothing of the more typical, family-type Democrats," like Short's own working-class Catholic family.

"For 76 years," one Short TV spot says, "Don Fraser has said yes to every spending scheme . . . Minnesota needs a senator who will say no, for a change."

Standing on the terrace of a lakeside condominium the other evening, at a fund-raiser organized by employes of his downtown hotel. Short, hoarse from campaigning, shouted over the sound of a fountain that "my opponent says I sound like a Republican." There was applause from the well-dressed crowd. "I have no objection," he said, and then asked Republicans in the group to support him in the PFL primary, as state law allows.

Fred Gates, Short's campaign manager, says he expects no more than a 2 percent crossover, but Fraser says that overt appeal to Republicans - as much as what he calls the distortions of his record - is why he finds Short's campaign "particularly offensive."

Uncompromising in his advozacy of traditional DFL liberalism, Fraser says he thinks "the conservatives including Short and the Republicans, have overestimated the depth of feeling about taxes and spending and have made a strategic error in thinking that any kind of cutback proposal would sell - no matter how sweeping and impractical.

"Minnesota voters are smarter than that," he says.

A few hours before Short was on the condominium terrace, Fraser, Anderson and Muriel Humphrey were in an overheated second-floor room above a Chinese restaurant in Duluty, where she told 150 DFL loyalists. "I find everyone asking me what's happened to the DFL since Hubert died? You've got to keep it together now. You've got to elect these two good people who grew up in the Hubert Humphrey philosophy and are the kind of liberal Democrats he was."

But even as she spoke, she was looking into a forest of "Dump Fraser" signs held up by right-to-life advocates, and by resort owners and employes critical of his strand on the Boundary Waters issue.

And, on the other side of the room, a women legistor with strong environmentalist backing maneuvered carefully to stay out of any photographs with Anderson, calling his campaign and his positions "a disaster."

Even in the face of that kind of divisiveness, both Anderson and Fraser went into the campaign's final weekend as favorites to win their primaries by a margin of 10 percentage points or more.

But they - and the DFL leaders - are worried that Short's campaign and the anti-Anderson sentiment could trigger upsets.

Optimists in the DFL think that if both Fraser and Anderson survive the primary, both may be able to win in November.

But several members of the OFL state ticket believe that a Short victory in the primary would doom Anderson and Perpich in November by sending the Fraser liberals home to sulk - even if Short himself beat Durenberger, as some of the Democrats think possible.

This year is critical for us," says state DFL chairman Ric Scott. "If we can make it through thei primary, we can continue the party Hubert Humphrey put together. But if we lose one of our candidates in the primary, I think it will be tough. Very tough."