By any standard, the Democratic Party should be in fat city. Unemployment is the highest in 40 years, there is a Republican to blame in the White House, and curing joblessness is supposed to be what Democrats do best.

The GOP, after repeatedly implacing itself on the issue of Social Security, is now trying to bury it by turning the outlay into an "off-budget" item. Bankruptcies have spread from Main Street to firms listed on Wall Street.

The Democrats, meanwhile, seem finally to have achieved some unity; the House Budget Committee reported out an alternative to President Reagan's budget last week on a party-line vote, with only one Democrat defecting.

But the Democrats remain divided and uncertain of their way. Some centrists rail at the liberals. "The bongos are all by themselves," Rep. Les Aspin (D-Wis.) lamented the other day, using a term he coined. "Their main concern is to increase spending in domestic program . . . They really don't care about the size of the deficit."sT"That's bull---," counters William M. Brodhead (D-Mich.), chairman of the Democratic Study Group and a certified liberal. "That's nonsense. Our skirts are clean in terms of those issues. That we want to spend $10 billion more than Reagan or the majority of Congress on social programs pales in comparison with #33 billion more in defense spending, pales in comparison with the tax giveaways."

So it goes among the Democrats. They are split, and as the recession continues and public support for the Reagan program apparently wanes, Democrats have yet to regain the image of a party equipped to present alternatives.

The House Budget Committee's approval of a Democratic budget resolution last week set in motion a test of the Democrats' ability to develop coherent policy in an increasingly anarchic House of Representatives controlled by the Democrats.

"At this point, the budget resolution takes on a life of its own, a symbol of our ability to gover," Rep. James R. Jones (D-Okla.), chairman of the Budget Committee, said after the 17-to-12 vote to send the resolution to the floor.

But Jones' assessment of what the budget should contain is already under attack from the Democratic left and right, which take diametrically opposed positions on such fundamentals as social spending, taxes and the military buildup.

In an economy where the driving force politically is the size of the federal budget deficit, ther is, in fact, a surprising degree of agreement among Democrats on the goal of eliminating the red ink. Liberals like Brodhead and David R. Obey (D-Wis.) contend that the triple-digit deficits under Reagan have given Democrats the chance "to become the party of fiscal responsibility."

However, there is little agreement after that. Rep. Charles W. Stenholm (D-Tex.), head of the Conservative Democratic Forum, the "Boll Weevils," complains that the Democratic leadership didn't make a "sincere attempt" to deal with the budget problems that his group perceives. Key members of the party's center complain, as Aspin did, that the liberals have an almost insatiable thirst for domestic spending. And the liberal wing sees the party's traditional goals being sold out in favor of stepped-up defense spending and an excessive tax cut.

The Democrats' dilemma has been reflected in numerous polls, including several by The Washington Post and ABC News. A March survey showed nearly half the public convinced, for example, that Reagan "really cares more about cutting taxes for the wealthy and eliminating social programs than he does about helping the nation's economy."

But the same survey found that 43 percent believe the Democrats have come up with no alternatives, 11 percent think Democrats have alternatives but theirs are worse than Reagan's, and 26 percent see the Democrats as having "better" alternatives.

House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.), symbol of the Democrats' generous past, has slowly and somewhat reluctantly become critical of his own party's spending and regulatory ventures of the last decade. Using the GOP epithet "wild spending," O'Neill contends that after the election of 78 new Democrats in 1974 in the post-Watergate environment, "we broke the system around here . . . .We over-regulated and we over-legislated," he said, gesturing to the House floor.

At the same time, however, aides contend that the speaker's basic strategy is to wait until the consequences of the Reagan budget and tax cuts sink in and, in this scenario, prompt a lessening of the public's anti-government attitude.

The ultimate goal, in this strategy, is a restoration of a political climate reuniting Democrats around "the basic issues . . . adequate health care, educational opportunity for all, adequate nutrition for the poor, the aged, and providing an economy that offers employment for all," according to O'Neill.

While not in direct conflict, there is a subtle and significant difference between the O'Neill posture and that of a number of key Democrats who, as budget battles come to dominate proceedings, have emerged as among the most influential in their party.

Rep. Leon E. Panetta (Calif.), a leader of the moderate Democratic faction on the Budget Committee, does not directly dispute O'Neill's goal of restoring public awareness of government's substantive benefits, but his first priority lies elsewhere:

"Management on the fiscal side. The public has to be convinced that we are concerned, that we have developed a better sense of management. It has to come first."

Panetta is not an opponent of O'Neill's, but he contends that the speaker "leans to going back to some of these basic programs . . . .His guts will always be with the policies that were." Panetta suggests that the party has to explore "new ideas . . . new approaches," but he is noticeably lacking in specifics, and remains far more comfortable talking about the procedural issues of management and budget making.

At the same time, the House Democratic leadership has often appeared to be operating on conflicting wave lengths. Majority Leader James C. Wright Jr. (D-Tex.) has been the leading sponsor of a measure to require a balanced budget and the leader of the battle to restore the Social Security minimum benefit that Congress cut last year to reduce the deficit. For a time last year, Wright and O'Neill were hardly speaking because of differences over strategy and leadership tactics, although the conflict has lessened lately, according to aides.

In the case of the Budget Committee chairman and O'Neill, however, there is considerably more potential for conflict.

Before he became chairman of the Budget Committee, Jones saw himself as a leader of the conservative wing of the House, a faction he believed would become the base of party strength as the electorate shifted to the right.

Jones used to go out of his way to point out the sharp differences between himself and O'Neill, and between what he saw as the O'Neill Boston district's heavy dependence on federal aid and his own Tulsa district's oil-based, free-enterprise vitality.

Since Jones became chairman and was forced by the need for accommodation to move toward the center of his party, the sharp edge has been taken off the differences between him and O'Neill, but there remains a strong tension.

While reluctantly supporting the Jones budget resolution, O'Neill has voiced concern that it represents the "bottom line" in terms of the scope of domestic cuts. The committee budget consequently is a dangerous bargaining vehicle, in O'Neill's view, when negotiations begin with the Republican-controlled Senate, which is considering a far more conservative proposal.

On the other side of the coin, Jones has signaled concern about whether O'Neill will follow through and give full support to the committee budget when it reachs the House floor.

Farther out on the ideological edges of the Democratic Party, there is little substantive disagreement between left and right over the goal of lowering the deficit, but the conflict over the means to achieve it has become increasingly bitter.

The House Budget Committee voted to increase defense spending by 5 percent beyond the expected inflation rate for each of the next three years. This is inadequate for the hard core of the Conservative Democratic Forum, while at the same time some liberals view it as excessive.

In terms of policy, Stenholm, Rep. Phil Gramm (D-Tex.) and other conservative Democrats are closer to Reagan than to many of their Democratic colleagues, not only on defense spending, but also in their reluctance to support increased taxes and in their advocacy of deep cuts on social programs.

In contrast to last year, however, when these conservatives defected to the Reagan tax and budget cuts in droves, there appears to be far less pressure on the more moderate members of the conservative forum to back Reagan.

According to Rep. W.G. (Bill) Hefner (D-N.C.), every time he went to meetings in his district last year, he would hear repeatedly "support the president. Now I go, and I just don't hear it anymore."

This year, in attempting to shape a majority in support of the budget resolution, the Democratic leadership will be struggling to win the votes of moderate Frost Belt Republicans from the Northeast and Midwest, known as the "Gypsy Moths," as well as from its own liberal wing.

However, some members of the liberal wing, to the dismay of the leadership, are already staking out positions that will make it difficult to pick up thR N Bynb' X6 Black Caucus who has remained close to the House leadership, said that, as the resolution is "presently crafted, I can't support it . . . . There are some who cling tenaciously to the old way of doing things, and I'm one of them."