Poland's military leader, Gen. Wojciech Jaruzelski, appears to have consolidated his hold on power during the past week by demonstrating that he has the support of both the Kremlin and the Polish Communist Party.

But, despite the applause of the carefully drilled Moscow crowds this week and his party's Central Committee last weekend, Jaruzelski still faces daunting problems. It is still unclear how he will be able to rule Poland without the protective shield of martial law, let alone extricate the country from its grave economic and political crisis.

The dilemma facing Jaruzelski was well-expressed by the official Polish government spokesman, Jerzy Urban, in a recent newspaper article. He compared the opposition movement to a genie that had been jammed shut inside a bottle on Dec. 13, when the military crackdown began.

"If the lid is opened, the genie will jump out. But if we keep it shut, the bottle may explode," Urban wrote.

In other words, the military authorities fear that if they relax martial law too fast, they risk losing control of events once again. But, unless they make some move toward reconstituting the now-suspended independent Solidarity union movement, they could face enormous popular unrest.

Judging by his speeches and actions so far, Jaruzelski's answer to this dilemma seems to be that he recognizes the need for reform--but is determined to control the process.

He summoned the Central Committee plenum and paid his first visit to Moscow since the imposition of martial law in order to get the green light for such a policy.

Official Polish commentators have several times suggested that Jaruzelski would like to emulate Janos Kadar--the Hungarian leader who, following the Soviet invasion of his country in 1956, gradually managed to reconcile his people to communism through a skillful policy of reform. Hungary is now the most prosperous and politically relaxed country in the Soviet Bloc.

The first indications are that both the Soviets and the Polish party would be prepared in principle to grant Jaruzelski a fair amount of leeway so long as he succeeds in restoring stability. But there are also strong political and economic forces at work that make the Kadarist objective of controlled reform a very difficult one to achieve in Poland.

The main political obstacle lies in the fact that Solidarity has only been bottled up, not eliminated. An essential element in Kadar's formula was that he embarked on reforms only after four or five years of political terror. Hungarians had to be convinced that reform could only come from above.

The main economic obstacle to Kadarism being applied in Poland is that, after 10 years of profligacy, there are no reserves with which to cushion the consumer from the harsh laws of the market. Living standards are already so low that it will require continued repression to persuade the Polish people to accept a further reduction. And that in turn could help destroy any remaining economic motivation for hard work.

In the absence of large-scale Western credits, Jaruzelski's dilemma can only be solved if the Kremlin agrees to finance major structural reforms with a massive package of economic aid.

In public at least, senior Polish officials profess optimism that the Soviet leadership can be persuaded that it is in its interest to mount such a rescue operation for Poland. A prominent sociologist, Prof. Jerzy Wiatr, said in an interview that he believes the Kremlin can live with the kind of market-oriented economic reforms now being proposed by the Jaruzelski government.

"The alternative to reform is economic collapse. Jaruzelski's own position would weaken--and the next crisis would be just around the corner. This the Soviets understand," said Wiatr who heads the Institute for the Study of Marxism-Leninism in Warsaw.

Most Western economists here are not so sanguine about the Kremlin's ability or willingness to support the kind of radical reform that would be necessary to restore the health of the Polish economy. The question of economic aid was certainly a major topic in Jaruzelski's talks with President Leonid Brezhnev this week. But, despite general Soviet promises of further large-scale assistance for Poland, no figures have been mentioned.

Western analysts agree that--viewed in the short-term political context--Jaruzelski's position seems practically unchallengeable. An expected move against him by the hard-line wing of the Communist Party did not materialize at the plenum--and the martial-law chief clearly has solid backing on the Central Committee.

Wiatr explains Jaruzelski's popularity among the 200 rank-and-file members of the Central Committee by pointing to a convergence of interests.

"Jaruzelski's political line reflects the concerns of the typical Communist Party activist. Before Dec. 13, these people felt both defeated and hunted by Solidarity. Martial law to them was like a burst of sunshine in a clouded sky.

"On the other hand, the majority of Central Committee members represent not the party apparatus but big factories. They're in daily touch with workers and want to win their approval. The hard-line option of repression is unacceptable to them. Jaruzelski's policy of combining vigorous defense of the system with an attempt at reconciliation therefore represents the best solution from their point of view," Wiatr said.

But those members who looked to hard-line former Politburo member Tadeusz Grabski as their leader, favor the restoration of centralized party rule and a total settling of accounts with Solidarity.

The real danger facing Jaruzelski is not that he will be unseated by the hard-line faction, but that he may be gradually forced to adopt its policies. The most obvious example of this process is martial law itself. The hard-liners had been advocating such a crackdown for months--but it was the relatively moderate Jaruzelski who actually implemented it.

The Central Committee plenum suggested that the only force now capable of swinging the political balance in the hard-liners' favor is the Kremlin. But, on the evidence of the hugs and kisses in Moscow this week, the Soviets regard Jaruzelski as their man.