On Sunday, 4 1/2 years after his declaration of martial law, Gen. Wojciech Jaruzelski will stand before Poland's communist party congress with the strength of a soldier who put an end to the country's greatest postwar upheaval and the weakness of a leader with few means to tackle the crippling aftermath.

As Soviet leader Mikhail Gorbachev looks on, Jaruzelski will be cheered by his party for restoring order to its ranks after a nearly calamitous 16-month confrontation with the independent trade union Solidarity in 1980-81. In evidence of this success, the congress of the Polish United Workers Party, the first since July 1981, should be as calm and controlled as the last was stormy.

Yet as Jaruzelski pleads for the implementation of his planned economic and party reforms, he will find few devoted cadres ready to support him. Instead, his program is likely to be greeted with sluggish reluctance by the party apparatus and weary cynicism by much of the Polish public.

The 62-year-old leader will almost certainly be elected with ease to head a Politburo more under his control than ever before. Close associates, however, say he will remain a modest, cautious ruler, stricken by self-doubt and acutely aware of his weaknesses in facing Poland's ongoing crisis.

After 56 months in power, this introverted, pedantic soldier with tinted glasses and stiff posture has emerged as Poland's most complex postwar leader, a man both saved and crippled by his deft ability to sidestep the dramatic gestures and bitter polarization that have dominated national politics.

Throughout his rule, as all during his 39-year career as a communist, Jaruzelski has combined an unquestioning fulfillment of duty to Soviet-imposed orthodoxy with a methodical pursuit of political balance. The result has been a paradoxical mix of outward success and inner failure, of achievements that are real but sometimes hollow because they are negatively defined.

Even Jaruzelski's one dramatic action, his declaration of martial law on Dec. 13, 1981, has this double character. Though a drastic step, it was mild compared to the Soviet invasions that followed earlier rebellions in Eastern Bloc countries. And though it crushed the hopes and spirit of millions of Poles, today it is defended and even celebrated by Jaruzelski for what it did not do -- the bloodshed it largely avoided, the lingering, de facto opposition it did not completely crush.

Such equivocal accomplishments can rarely spark enthusiasm, and today one consequence of Jaruzelski's tactics has been his relative isolation in a political vacuum of frustration and apathy. Outside a narrowing circle of mostly military associates, he has no strong base of support in the party, government or society. Though he has no rivals, he also has no strength to implement the forceful measures that most Poles believe are needed for long-term stability and development.

"What is lacking is the real power of implementation, and he knows it," said one former communist activist, echoing one of the most common evaluations of Jaruzelski. "He is strong, because he has eliminated all alternatives. But what guarantees have been provided to avoid the next crisis? What socio-economic problems have been solved? What important social groups have rallied behind the government in the last four years? The answer to all these questions is 'none.' "

The answer of Jaruzelski's associates is that the general's intention has never been to conquer such sweeping problems. "He has never sought to win over millions on one day," an aide said. "Instead, his ambition is to take small, certain steps, to win over one person in Poland every day. He avoided some steps to create democracy, but he also avoided some big repressions. I like his small steps, because they keep us out of big crises."

Even with the country subdued and his personal position secure, Jaruzelski now appears to have no intention of altering his strategy. Instead, he hopes to offer the country the prospect of slow, tedious but consistent progress toward economic stability and, over the years, to win over or wear out his opponents in and outside the party.

The open question he faces is whether such a minimalist, uncharismatic approach is appropriate to a nation of such dramatic troubles and divided emotions. So far, argue his critics, Jaruzelski's small advances have been largely illusory, the result of short-term police tactics and economic pump-priming.

Jaruzelski acknowledges the risk. "Impatience and rejection of stagnation can be a lever of effectiveness . . . if we convince people of the real reserves and possibilities, if we indicate ways of improvement and organize work properly," he told a party conference. "If we fail to do this, social expectations can turn against us. Hope will give way to mistrust, passivity, apathy."

To some degree, Jaruzelski's record of ambiguous positions and indecisive half-steps is a product of the multisided political struggle he inherited. Faced with the need to satisfy Soviet overseers, western creditors, a powerful Roman Catholic Church and a rebellious society, the general has always faced unavoidable and conflicting demands for liberalization and police-enforced order, economic reform and socialist orthodoxy.

But even if his room for maneuver has been tightly limited, Jaruzelski's style has also appeared to be the product of a character that, forged during a youth of sweeping upheavals, has been marked ever since by a perfectionist's absorption in well-defined tasks and an instinct for quickly finding the safe side of conflicts outside his control.

Born in the eastern village of Lezow in 1913 to a family of land-holding small nobility, Jaruzelski had the upbringing of typical prewar Polish gentry before World War II and its aftermath shattered his family, lifestyle and class.

Although his biography has never been officially detailed, Jaruzelski's family is known to have been deported to Siberia after 1939 by the Soviet occupiers of eastern Poland, and Jaruzelski's father is believed to have died there in 1943 after being placed in a forced labor camp. After the war, during which Jaruzelski eventually fought with a Soviet-formed Polish army, his family's property was confiscated, and the eastern region of Poland to which he had fled from the Nazis was permanently annexed by Moscow.

With an army career his only reasonable alternative, Jaruzelski joined the communist party in 1947, attended the infantry college and the general staff academy, and found a way to survive and even prosper from the kind of national upheavals that had once changed his life beyond control.

Critical students of the general's past say he consistently gained through unflinching loyalty to prevailing powers. During Poland's de-Stalinization crisis in 1956, these sources say, he was one of only three generals who did not support a petition to oust the Soviet general then serving as Poland's defense minister. Named as defense minister himself in the midst of another political crisis in 1968, he loyally carried out a purge of the Army's Jewish officers as part of a general hard-line move in the party, then directed Poland's role in the Soviet-led invasion of Czechoslovakia four months later.

When Polish workers rioted in Gdansk in 1970, touching off another crisis, Jaruzelski was one of the participants in a high-level meeting that decided to use troops and live ammunition to quell the unrest. Later, as the top communist leadership was purged for that decision, he was the only figure who survived and was promoted to the Politburo.

Finally, in managing Poland's crisis since 1981, Jaruzelski has made the reestablishment and consolidation of totalitarian order -- and Soviet security -- his first concern and has not hesitated to use police tactics to accomplish his aim. Within that framework, however, he has sought to conciliate the public and western governments by limiting repression and offering initiatives such as repeated amnesties for prisoners, limited legal and electoral reforms, and tolerance for relatively open economic debate.

"Jaruzelski's idea is that he can do things for Poland while remaining 100 percent loyal to the Soviet Union," said Ryszard Reiff, a former member of the Council of State. "Every time he moves to satisfy the Soviet interest, he tries to compensate with a gesture to society."

No measure, no matter how extensive on paper, has gone untempered. New laws ordered by Jaruzelski have created the possibility of a sweeping crackdown on underground opposition activity and a thorough purge of institutions such as universities, but have never been fully implemented. At the same time, far-reaching changes in the centrally managed economy enacted by the parliament years ago have never been fully forced on a reluctant party bureaucracy.

While systematically purging the party of both liberal and hard-line rivals in the last four years, Jaruzelski still tailors speeches and occasional crackdowns to party members who favor orthodox socialist economic principles and a tougher approach to the opposition. And though he has been uncompromising with Solidarity leaders, he frequently appeals to the union's former members to help him push economic changes past a bureaucracy entrenched in "the old ways."

The two most obvious consequences of Jaruzelski's rejection of more radical steps are that Poles' living standards remain 20 percent below the level of the late 1970s, despite three years of slow gains, and that a substantial opposition still works against the government, despite thousands of jailings of activists in the last four years. Opposition sources say more than 320 political prisoners are being held.

The result is that the general lacks the active support of any substantial internal constituency. Many rank-and-file workers, especially in the party, resent the costs of economic reform, while supporters of reform, most of them former Solidarity members, have been alienated by political crackdowns. Party hard-liners have bridled at repeated amnesties for prisoners, while the western governments that were the targets of such gestures have been turned cold by news of new repressive laws and repeated arrests of famous Solidarity leaders.

As the party congress opens, Jaruzelski's strongest political support may lie in the Soviet leadership of Gorbachev, which has strongly embraced him in the last six months. Yet Jaruzelski appears to remain visibly distrustful of the party's civilian apparatus and insecure about political moves toward the church or opposition that might risk Soviet displeasure.

Much as he did four years ago, Jaruzelski continues to depend heavily on a small circle of associates drawn principally from the Army. Most lists of his closest advisers begin with Defense Minister Florian Siwicki, Interior Minister Czeslaw Kiszczak, Government Council of Ministers Coordinator Michal Janiszewski and Mining and Power Minister Czeslaw Piotrowski. All are generals.

Associates say the general now works harder than ever, steeping himself in the details of party operations. "He reads every piece of paper in the party," said one aide. "He's a pedantic personality and a workaholic. He may be taking up too many small questions."

Jaruzelski still goes through multiple drafts of speeches without being satisfied, and texts for publication often are delayed while he makes last-minute changes. He can agonize for weeks or months over decisions, especially involving the economy, and is quick to blame himself for initiatives that turn sour.

"He never has the feeling that he has succeeded," an aide said. "His thinking is, 'I did something but it could have been much better.' He is not pessimistic, but he is not upbeat. He believes it is no time for wonders -- not in Poland."