WARSAW, NOV. 24 -- Poles vote Sunday for the first directly elected president in the country's history, with final opinion surveys showing Solidarity leader Lech Walesa comfortably ahead of Prime Minister Tadeusz Mazowiecki and four other candidates.

Walesa, who has conducted a bombastic campaign, promising to streamline Poland's decaying industry without increasing unemployment, will be forced into a runoff Dec. 9 if he fails to win more than 50 percent of the vote.

And if he does win the presidency, he will face an extraordinary challenge of leadership. Pledged to "acceleration" of economic reform, Walesa will have to speed up the closing of money-losing industries while at the same time preventing paralyzing labor strikes, the first rumblings of which began this week.

"As president, Walesa will have a constant internal struggle between being union leader and leader of all the society," said Jan Malanowski, a prominent labor sociologist.

Poland, which led the way in Eastern Europe's overthrow of Communist rule during the 1980s, may now provide a guidepost to the ability of the new democracies to cope with the difficulties of economic change while retaining their new commitment to freedom.

The 8 million Poles who work in state-owned industries go to vote in Sunday's election knowing that for them the worst times are still to come. Next year, Poland's "shock therapy" reforms will hit state-owned industries with a vengeance.

Until now, according to a recent study by U.S. economists, the impact of free-market reform on state-owned industry has been limited. The report says ex-Communist managers have postponed hard management decisions by cannibalizing their industrial plants. As a result, there have been relatively few layoffs, relatively little modernization and very few bankruptcies.

In 1991, the government will try to speed the sale of the healthiest state-owned industries to private buyers. Among the thousands of unprofitable companies, there are likely to be huge layoffs and bankruptcies. The government expects layoffs, 700,000 this year, to double.

Next month, the government will make public a list of 20 unprofitable hard-coal mines (out of 71), that are to be phased out in three to 10 years. These large-scale closures will be catastrophic in some regions, like Walbrzych, in the economically depressed southwest, where 19,000 miners will be without work.

Of the six presidential candidates on Sunday's ballot, Walesa, the Solidarity union leader, has the strongest support from industrial workers.

According to a state television survey taken Monday and Tuesday, Walesa held a comfortable lead with 38 percent of those polled, Mazowiecki had 23 percent and Stanislaw Tyminski, a businessman recently returned from exile in Canada, had 17 percent.

For workers and their families -- the largest segment in Polish society -- the economic hardship will be made worse by a drop in social status. Despite two decades at the vanguard of anti-Communist revolution, and decades of Communist rhetoric that assigned them superior moral and ideological status, Polish workers are downwardly mobile.

"The workers are losing the position of influence they had at the moment of the changes. They initiated the change, and now they feel they've lost irrevocably their position; there is a general feeling of decline," said Jan Litynski, a longtime Solidarity activist, now a deputy Labor minister and member of parliament.

Despite their lionization in Communist tracts, Polish workers have higher rates of serious disease and suicide than any other group in Polish society. Today, the child of a worker is less likely to attend a university than he or she was in the 1950s, according to labor sociologist Maria Jarosz.

This decline is felt keenly by many of the 2.3 million workers of Solidarity. "In 1981, a Solidarity activist was very influential in the factory and his region," Litynski said. "Now there are new democratic institutions that fulfill those functions."

This week, roughly a fourth of the coal mines in the country went out on strike, defying both the government and the union leadership, which threatened to expel the dissident locals. Simultaneous strikes by transportation workers crippled traffic in Krakow, Gdansk and other major cities.

The gloom was especially deep at the Kazimierz-Juliusz coal mine near the town of Sosnowiec in southern Poland, where 19 red-eyed, disgruntled coal miners, 16 of them Solidarity members, are staging a wildcat hunger strike to protest static wages and falling government subsidies to their state-owned mine.

Last year, jubilant coal miners at the Kazimierz-Juliusz mine were the first in the country to toss their corrupt, coffee-swilling Communist supervisor off the payroll. Now that jubilation has burned away.

"Everything was so simple and clear last year. It seems like a dream," said Aleksander Boron, a Solidarity activist at the mine.

"Sometimes I feel so ashamed, because we made promises and now we can't keep them," said Marek Janosz, the Solidarity firebrand who helped oust the mine's corrupt Communist boss last year. "I didn't promise we'd be rich, but I thought we'd have control of our own mine. Instead, the {ex-Communist} managers still have their privileges, and we look bad for complaining."

At Kazimierz-Juliusz, as elsewhere, the coming of a new economic order has meant the ebbing of old socialist perquisites.

Once the highest paid industrial workers, coal miners have watched bitterly this year as their wages neared parity with easier occupations such as bus and streetcar driving.

Food prices, no longer kept low by subsidies, have climbed several hundred percent. Miners -- whose wives usually do not work outside the home -- no longer save money, and sometimes they do not have enough for food.

"By mid-month, a coal miner has to spread jam on his bread because he has no meat or sausage," said miner Wieslaw Koziol.

The free high-energy soup that miners once were guaranteed after a shift below ground has gone, too. And mine buses are no longer available free of charge for family outings.

The miners at Kazimierz-Juliusz pledged this week to continue their hunger strike "until the end," but in private several Solidarity activists were more pragmatic. "If I were the government I wouldn't give in; it would start an avalanche," said Dariusz Oko. "But we have to ask."