Just a few weeks ago, the Warsaw steelworks was considered a stronghold of the Polish Communist Party. Then came the strikes of last August. Today, the plant es a stronghold of the newly established independent union, Solidarnosc (Solidarity).

The local branch chairman of Solidarnosc, Saweryn Jaworski, says he has the support of at least 9,000 steelworkers out of a labor force of 11,000. His claim is confirmed by the chairman of the official union, Edward Plusa, who talks about giving up his office job and returning to manual work.

The differing fortunes of men like Jaworski and Plusa provide a useful insight into how events have moved in Poland since agreement to establish new independent unions were signed a month ago. In those plants where it is active, Solidarnosc has won the backing of between 80 and 100 percent of the work force. But it claims to be meeting obstacles from management in smaller factories not directly involved in last summer's labor unrest.

On a personal level, relations between the rival union leaders at the Warsaw steelworkers are cordial. But Jaworski has firmly rejected Plusa's offers of cooperation and the suggestion that they should fuse their two organizations into a single, reformed union.

Solidarnosc's hold over the Warsaw steelworkers was illustrated by the response to last Friday's one-hour nationwide strike. A huge majority of workers, including some members of the official unions, showed their support by wearing red and white armbands and flying the Polish national flag.

Jaworski, 49, marched through each department of the huge steel works accompanied by members of the strike committee. Chanting slogans like "no more lies" and "no decisions about us without us," he waved a clenched fist at groups of workers. There were smiles, cheers, and answering fist waves in return.

Meanwhile, Plusa, 41, was sitting in his nicely furnished office in the management building. He handed out key-rings bearing the insignia of the communist-dominated metalworkers' union, explaining with a sad smile: "I may as well get rid of these as it looks as if we'll soon be extinct."

In private conversation, Jaworski tends to speak as if addressing a public meeting. A furnace supervisor with a wispy beard, he enunicates every word with the conviction of a man attempting to drum an obvious truth into a stubborn opponent. He is scathing about the old unions which, he says, lost the workers' trust by behaving as a creature of the management.

"There has been dissatisfaction here for years, particularly over pay and working conditions. But the old unions disregarded our opinions and were totally controlled by the party. Their function was to act as a kind of loudspeaker for management, constantly urging workers to fulfill the plan," he says.

When Solidarnosc was first established after the August strike, it encountered difficulties in many plants including the Warsaw steelworkers. At first, the management was reluctant to recognize the new union as representatve of the workers.

A crucial battle was fought over the right to inform workers of union activities. Solidarnosc sympathizers pasted up leaflets around the plant explaining how to sign up for the new union. The notices were torn down by party activists and Jaworski was not allowed access to the public-address system such as he had enjoyed during the original strike.

Solidarnosc responded by ostracizing the activists and issuing what Jaworski describes as "warning signals" about industrial action. Eventually, the union was given its own office and bulletine boards. With the manager's permission, Jaworski is allowed to address the workers over the public-address system.

The steelworkers branch of Solidarnosc has its own well-produced newspaper called Voice of the Free Trade Unionist. It is printed free of charge on the plant's offset press and includes a mixture of union communiques, a serialized blow-by-blow account of the strike in Gdansk and discussion of workers' grievances.

There is even a cheeky section devoted to the selected thoughts of Karl Marx. Samples: "No one can fight for a cause without making enemies." "The fist is the last argument of the crown. The fist will be the last argument of the people."

Plusa is envious of the priveleges granted to Solidarnosc. He commented wistfully: "We never had these advantages. Previously when we went to management with our grievances, they wouls always tell us this was not the right moment, that we should hang on and wait and everything would be settled later. But it never was."

At the steelworks, which is one of the largest employers in Warsaw, there seems little doubt that the old union will eventually wither away completely. After two years as the union's chairman, Plusa himself talks about returning to his old job as section foreman. Eight other full-time employes of the union will also probably soon be looking for work.

For the moment, until Solidarnosc achieves full legal status, the official union is carrying on with its regular administrative work. It is still responsible, for example, for dividing social benefits among the workers and settling insurance claims. It also runs several holiday homes and rest houses. But it is likely that control will eventually be transferred to Solidarnosc.

In an effort to compete with Soldiarnosc, the metalworkers' union disaffiliated from Poland's Central Trade Union Council and declared itself an autonomous body. But this maneuver has done little to reverse its swiftly declining membership.

The old union is, however, in a stronger position in smaller factories. Jaworski mentioned a scrap metal processing plant, Centrozlom, near the steelworks. Here the management is still refusing to recognize the Solidarnsco founding committee and insists on dealing solely with the official union.

Many Communist Party members have become active in the new unions. Of the 14 members of the Solidarnosc founding committee at the steelworks, seven are also party members. This compares with a much lower proportion of party members in the plant as a whole -- just 27 percent.

These figures underline the strong dissatisfaction of the party's own rank and file. At its higher levels, particularly the Central Committee, the Polish party is still a very conservative organization. But many ordinary members, who kept silent at party meetings for years, are now beginning to speak out.

Plusa confessed he was taken aback by the escalation of workers' demands and the transformation of social attitudes at the steelworks. He agreed with many of the criticisms directed against the old unions and blamed the lack of effective political structures for expressing discontent in the past. But he also said he was concerned at a sharp fall in productivity at the plant.

According to his figures, the steelworks lost around $6 million in August and another $1.3 million in September. Production is now well below planned targets. This is partly because of shortages in raw materials and supplies from other factories, but partly also because workers spend much valuable time engaged in political discussion.

Similar losses have been recorded elsewhere. Some Polish commentators interpret the mood of excitement and intense debate as a necessary and cathartic consequence of the social upheaval through which the country has passed. Others fear that, unless some order is quickly reestablished in the economy, there could be a danger of a Stalinist backlash among hard-liners in the leadership.