Fifty-two weeks ago today, in a moment of extraordinary historical symbolism, President Jimmy Carter of Plains, Ga., stood in the rotunda of the Capitol by the casket of Sen. Hubert H. Humphrey of Waverly, Minn., and praised the man he said "gave us a vision of what we are at our best -- and of what we might become."

The only Democrat to serve as president in the 1970s spoke of the man who had been at the center of his party's battles in the 1940s, 1950s and 1960s as "an inspiration and a conscience to us all."

He praised Humphrey as "a clear voice, a strong voice, a passionate voice" for every cause -- from civil rights to social justice to world peace -- to which a generation of Democrats had responded.

A year later, Carter finds himself at the center of the increasing pressures, tensions and anxieties generated by divergent elements of a party, which, for all it spower, no longer seems certain of its purpose.

The man who united what he rightly called " a divided Democratic Party" just enough to achieve the office Humphrey was forever denied is finding it a harder task to give his party definition in a time of transition.

This week, as the Democratic Congress returns and Carter prepares the State of the Union and budget messages, which will set the party's course for the last two years of his term and for the 1980 election, the Democrats are both politically prospering and perplexed.

Few of them claim a clear "vision of what we are." And even fewer have any confidence that they know, for the 1980s, "what we might become."

Consider the paradoxes. As evidence of their strength, Democrats can cite the fact that their party:

Is now the oldest and probably the most successful political party in the western world.

Has controlled the presidency for 30 of the last 46 years and Congress for all but four years in that time.

Held losses in the midterm election to the minimum, by historical standards, and emerged with more than 60 percent of the seats in Congress and the state legislatures, 32 of the 50 governorships and the mayoralities of 43 of the 50 largest cities in the land.

Is identified in the public mind as "the party of the common man" and is viewed as their political home by almost twice as many voters as call themselves Republicans.

Has a president who leads all prospective Republican challengers in trial heats for reelection in 1980.

On the other hand, the Democrats are also a party which:

Has been unable to renominate or reelect a president to a second term since Franklin D. Roosevelt in 1936.

Has failed to get more than 50.1 percent of the votes in the last three presidential elections.

Has been a steady decline in the turnout of its electoral base for the past 18 years, and has been unable to escape debt for the last decade.

Has an incumbent president who consistently trails an intraparty rival, Sen. Edward M. Kennedy (D-Mass.), in polls for the 1980 nomination.

Is led by a man who is described by both his predecessor as party nominee and the president of its largest allied constituency group -- George McGovern and George Meany -- as being more Repulican than Democratic in his policies.

Has not recovered from the foreign policy split which drove it from power 10 years ago and, therefore, depends on Republican votes to sustain its most basic international policies.

And is sufficiently unsure of its direction or purpose that its national chairman is seeking foundation funds for a study of what it should be doing.

There was no one among the three dozen party leaders interviewed for this article who did not -- in some way -- express the perplexity of the current situation for Democrats.

"I think we're in pretty good shape," said Vice Preisent Mondale. "We came out of the last election most recently, the leaders of the party's activisit, women have expressed their strong dissent from Carter's economic policies. And their view has been championed by Kennedy, the man most Democrats say they would prefer to see as president.

Yet, among leading Democrats, there is virtual unanimity that changing circumstances -- from the energy crisis to presistent inflation to Proposition 13 -- dictate some changes in the direction and policies of their party.

Their worry is that they have not yet found the elusive formula that adapts to the new realities without sacrificing the old values for which Humphrey preeminently spoke.

While presidential assistant Hamilton Jordan and House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.), surveying the Democrats from their perches of power at opposite ends of Pennsylvania Avenue, join Mondale in finding the party "in pretty good shape," others note serious symptoms of at-least-incipient malaise.

"The Democratic Party," says Sen. Gary W. Hart (D Colo.), "is adrift." "I see a vacuum right now, really," agrees Rep. Norman Y. Mineta (D- Calif.). "Just a lot of thinkering and holding patterns."

Peter D. Hart, a leading Democratic pollster, says that, "When you ask voters about the Democrats," you get answers that are 40 years out of date. You get the New Deal stereotypes."

And Richard Conlon, veteran staff director of the liberal House Democratic Study Group, declares, "Our biggest problem is that we don't have any program anymore."

"Actually," he says, "we've been without a program for about 10 years quite well... and the president is now a seasoned president, which contributes to the strength of the party.

"But the test that is imposed upon the Democrats in the next four or five years is somewhat different than it's been historical... We have a range of problems that are distinctly different and require a different kind of leadership, less susceptible to bill-boards and signs and simple answers," he continued.

"We have to deal with the problem of how you make a program that was noble and grand in concept work in the grimy day-to-day administration with limited resources and intergovernmental jealousies and changing priorities... so that it's efficient, cost-effective, so that it builds public trust, rather than undermines it.

"Otherwise," Mondale said, "public support for intervention in pursuit of social justice, the environment and our other goals will be undermined, and a new kind of political leadership will take our place who are far less anxious to achieve these goals.

"If we're going to win this," he said, "the party itself and party members have to join with us in understanding this complex, intractable range of problems that we face. It's a problem for us in positions of leadership to explain it in a way that they see what we're trying to do. And I'm not sure that we've done as well there as we should."

Outside the White House, most Democrats say flatly they have not. At the miniconvention in Memphis last month, where Carter and Mondale both tried to rationalize the new policy of budgetary austerity, it took all the muscle the White House could muster to defeat a hastily organized rebuke to this change of party direction.

The leader of the AFL-CIO, the president of the United Auto Workers, the chairman of the Congressional Black Caucus, the head of the Democratic mayors' association and, now, quite frankly. It's just been covered up by the war, by Watergate and other issues that have popped up. But-the truth is we have no sense of direction as Democrats."

Even within the White House, there are those who acknowledge that point.

"Nationally, the Democratic Party is okay," says Anne Wexler, the president's assistant for public liaison, "but it is not as strong as it was 10 years ago, and it doesn't have the credibility. It is in transition, and I don't know what it's in transition to."

The word "transition" was used so often in these interviews to describe this stage of the Democrats' history that it almost became a cliche. But for those in Congress or the executive branch, whose public lives spanned the gap from Humphrey to Carter, there was no mistaking the dimensions of the change that has taken place.

Rep. Lee H. Hamilton (D-Ind.), the president of the big class of Great Society Democrats elected on the Lyndon Johnson-Humphrey coattails in 1964, puts it this way:

"Those of us who came in the '60s, and perhaps earlier, came out of a period when the liberal philosophy was clear and tended toward a government solution... I think there's a marked change in the ideology of younger members that reflects the mood of the country. It's much more antigovernment, maybe conservative, with much more emphasis on making government work better."

Tip O'Neill, who confirms Hamilton's description of the change, notes that the younger members are now dominant in the House.

"For the first time in the history of Congress, I think, the majority of our members - 237 of them -- will be people who've come here in the last four years," O'Neill said. "And the average age of that group is 41 or 42."

Joseph A. Califano Jr., the former Johnson White House aide who now runs the Department of Health, Education and Welfare, talks of the change from "the expansive '60s to the more hesitant '70s," and says that at the end of the '70s, "the challenge for the American liberal is the challenge of austerity."

Dehaps the most thoughtful analysis of the altered conditions that forced this transition in Democratic Party policy was furnished recently by Stuart E. Eizenstat, Carter's assistant for domestic policy and one of the few senior staff members in this White House who once served as an aide to Humphrey.

In a major speech, Eizenstat ticked off the characteristics that make what he called "an era of constraints" so different from Humphrey's time:

An altered governmental structure, in which the moral authority of the presidency has been reduced, Congress has become both more assertive and more decentralized, the cohesive forces of the political parties have been weakened and the influence of special-interest groups increased.

An entirely different economic setting, characterized by a huge increase in the costs of mandated federal social programs, high deficits and persistent inflation.

And a changed climate of public opinion, marked by a growing awareness that resources -- both natural and fiscal -- are limited, a more skeptical attitude toward government programs and a greater resistance to the taxes that support them.

That view of the world is shared by some Democrats outside the Carter circle. For example, Sen. Hart has been suggesting in a series of speeches that "the failure of consensus" in his party can be remedied by new policies based on a recognition of a very similar set of "new realities": limited resources, a demand for greater governmental efficiency, more reliance on private sector and market mechanisms, and acceptance of "steady gains, not governmental miracles."

And Sen. Daniel P. Moynihan (D-N.Y.), the flamboyant social scientist-turned-politician, who is, like Hart, viewed by some Carter loyalists as a potential threat to the president, has his own formulation of the same theory.

"The task of the Democratic Party," he says, "is to manage the leveling off of the great S-curve growth in the public sector over the past 45 years."

Neither Hart nor Moynihan is surprised that Eizenstat's speech and Carter's policies drew a cool response from traditional Democrats.

"Most of the party cadres don't know this," Monynihan says. "They don't recognize it as necessary, or they say it might be necessary because of inflation or Proposition 13 or something, but they don't see it as good government."

And while Hart credits Carter with being "the first Democratic president to recognize the new limits and proscriptions'" he sees the transition as being "the process of at least a decade, and we're no more than halfway through."

"A lot of the fundamental premises have not been accepted," he says. "It's a generational phenomenon. They are more accepted by the newer, younger Democrats less aligned with the premises of the New Deal. But they are not accepted at all by many of our leaders who grew up in the old traditions."

Nowhere is there clearer evidence of Hart's theory than in the difference between his view, as a man of 41, and the attitude of the man whose presidential campaign he managed, George McGovern, 56.

To McGovern, Carter is a man who "for various reasons has chosen to follow a very cautious, conservative approach on domestic policy... much closer to what one would expect, say, from a Jerry Ford than from a Democratic president."

"I think it's not healthy for the Democratic Party to have that kind of confusing and blurred leadership at the top... I think the Democratic Party is raising a credibility problem for itself by essentially adopting a Republican philosophy," he says.

The notion that Carter is a closet Republican is not a new one. In July 1976, Walter Dean Burnham, the political scientist, wrote in the New Republic that "Carter's nomination by the Democratic Party will [WORD OMITTED FROM TEXT] political force is now in receivership." A year later, journalist Christopher Lydon suggested in Atlantic magazine that Carter was really "a Rockefeller Republican."

But that thesis is roundly rejected in the White House -- and by no one more vigorously than by Carter.

"I am proud to be a member of the Democratic Party," he told the party's midterm conference. "I am proud to belong to the party of Adlai Stevenson and Hubert Humphrey, of John Kennedy and of Lyndon Johnson."

"I have no alternative but to bring inflation under control," he said, and the budget cuts necessary to that end "will require that short-term sacrifices be made."

"But," Carter said, "we will balance those sacrifices fairly. If we err in this balance, it will be on the side of those who are most in need. That's the way Democrats govern."

If a man may be judged by the company he keeps, Carter can claim to be a mainstream Democrat, at home with his party's northern liberal wing. Of the 29 senators and representatives who scored over 80 percent support for Carter on Congressional Quarterly's compilation of presidential policy test votes in the 95th Congress, only one (Arlington's Rep. Joseph L. Fisher) came from below the MasonDixon line). Only two were rated below 50 percent approval by the liberal Americans for Democratic Action. Fifteen of the 29 who supported Carter at least 80 percent of the time were also that high in their ADA scores.

If the president were seated among his apparent soul-mates in Congress, he would find himself in liberal precincts. In the Senate, for example, he would be with John H. Glenn Jr., Alan Cranston, Paul S. Sarbanes, Patrick J. Leahy, Harrison J. Williams, Adlai E. Stevenson, John C. Culver, and yes, Stevenson, John C. Culver, and yes, Howard M. Metzenbaum.

Yet it is those same liberals who are most critical of Carter. Metzenbaum fought his energy policy as bitterly as anyone in Congress, and Culver had a barbed exchange with the president at the Memphis miniconvention on defense-vs.-domestic priorities.

The legislators who are most consistent Carter supporters also raise the thoughest questions about his leadership of the party.

"My concern," says Rep. Paul M. Simon (D-Ill), whose presidential support score was the highest in 1978 of must be "white-collar and professional, college-educated, middle-income, younger, suburban" voters.

"These are voters who are often, however, cautious on the questions of increased taxes, spending and particularly inflation, an issue which mobilizes this group in a conservative fashion," he said.

In the 1976 campaign, Caddell said, Carter lost his early lead among this group of voters -- and very nearly the election -- when the Ford campaign "did a fair job of typing Jimmy Carter to the Congress and to those negative aspects of the Democratic Party image that involve federal spending. The cautious, cheap' Jimmy Carter of the primaries was to some extent transformed into a typical 'expensive' Democrat."

To overcome that reputation, Caddell said, Carter must devise a program that "cuts across traditional ideology," even though "it runs the risk of alienating the ideologues on both sides."

When he was asked about his memo the other day, Caddell quickly agreed that "basically, it's been carried out." But he insisted "it was not as much choice as circumstance" that dictated the strategy. "Nothing else would have been realistic," he said "to have introduced a Great Society program would not have met the reality of the times."

In his view, the pollster said, Carter has "legitimized more than he has imposed" a change in approach of the Democratic Party.

"He has not corralled Democrats or even produced a definable theme and any House Democrat, "is that we're just holding our fingers to the wind, rather than asking, 'where should we go?'"

"I like Pat Caddell," Simon said, referring to Carter's pollster, "but I think one of the best things Carter could do would be to forget the polls and be a little bit more like Harry Truman and say, 'Let's go where we need to go.'"

McGovern, who also had Caddell as his presidential campaign pollster, agrees with Simon on that point.

"Carter campaigned on a traditionally liberal Democratic platform," he says, "and then pretty much forgot about it after the election... I think what happened after that election turned out as close as it did was that Carter was persuaded by some of his advisers that what he had to do to enhance his chances for reelection was to move closer to the position of Ford and the Republicans."

Caddell's post-election prescription for the Carter presidency -- revealed when a Dec. 10, 1976, memo he wrote for the president became public in the spring of 1977 -- makes fascinating reading today, in the light of the events of the past two years.

Noting that "governing with public approval requires a continuing political campaign," Caddell outlined a strategy "for the construction of a [new] political coalition based on a sucessful Carter administration."

Speaking of the Republican opposition, he said, "We have an opportunity to co-opt many of their issue positions and take away large chunks of their presidential coalition by the right actions in government. Unfortunately, it is those same actions that are likely to cause rumblings from the left of the Democratic Party."

Suggesting that Carter devise a program "that cuts across traditional ideology," Caddell said that, in terms of their growing numbers and political potency, the most important target program of his own. He did not dictate the campaign posture Democrats took in 1978; they took it on their own. But he has legitimized the change that has taken place," Caddell said.

Certainly, it is true that there are strong echoes of Carter's budgetary austerity in the programs announced this past week by Democratic governors from California to New York.

"Look at what they're saying," Moynihan exclaims. Jerry Brown [California Gov. Edmund G. (Jerry) Brown Jr.] says the historic mission of the Democratic Party is to reduce the size of government. Hugh [L] Carey says New Yorkers are insisting that government is no longer a growth industry."

Brown has leaped to Carter's right by espousing the Proposition 13 economies he opposed up until the moment of its passage last June, and advocating a constitutional convention to require a balanced federal budget except in time of national emergency.

Other Democratic governors, with similar liberal backgrounds, like Connecticut's Ella T. Grasso and Colorado's Richard D. Lamm, are also exposing taxcutting philosophies unfamiliar to their early supporters.

Like Carter, they are denounced as turncoats by the organizations of urban, minority, liberal and labor activists in their states.

But there is one difference. Those governors have all just won reelection -- and handsomely. None of them has to govern while also worrying about being renominated by a party whose leaders are eager to fight about everything from quotas for women to arms agreements with the Soviet Union, and whose voters say, all things considered, they'd rather it was Kennedy in the White House.

Next: How serious are the Democrats' divisions ?