By Agnieszka Barteczko and Adrian Krajewski
WARSAW (Reuters) - Poland's eurosceptic Law and Justice party (PiS) will have to wait for the final vote tallies before deciding whether to seek a formal political partner after crushing the incumbent pro-EU government in elections on Sunday.
Exit polls covering 90 percent of polling stations showed three smaller parties, including the leftwing alliance that grew out of the pre-1989 Communist Party, teetering on the edge of the threshold for entering parliament.
That might make for some political horsetrading over the next few weeks but will not weaken the decisive swing towards Law and Justice's brand of social conservatism mixed with left-leaning economics. Official results are due on Tuesday.
The victory for Jaroslaw Kaczynski's group returns it to power for the first time in eight years and is the biggest in terms of seats by a single party in free elections since Poland shed communism in 1989.
The party immediately signaled plans to reap new revenues from next year with a tax on bank assets, and there were also signs that it was confident of enough informal support in parliament from other parties to plan changes to Poland's constitution.
"Many party leaders have talked of wanting deeper change in Poland so, if we want to deliver that, changes to the constitution are vital," the party's spokesman on economic affairs, Zbigniew Kuzmiuk, told Polish public radio.
Shares in some of Poland's biggest banks fell sharply on Monday but the zloty was only marginally lower, reflecting the assumption of many investors over the past month that a PiS victory was likely.
Poland has seen its economy, the largest in ex-communist central Europe, expand by nearly 50 percent in the last decade, with the pro-market Civic Platform focusing on trying to make the most of EU aid and combining green-field investment with fiscal prudence.
But pockets of poverty and economic stagnation remain, and PiS was able to exploit growing frustration in some areas that the fruits of economic success are not more evenly shared.
ANGER AND DISAPPOINTMENT
Distrustful of the EU and an advocate of a strong NATO stance in dealing with Moscow, PiS opposes joining the euro zone any time soon and promises more welfare spending on the poor.
It also wants to enshrine more Roman Catholic values in law, reflecting the party's deeply socially conservative stance. Those ideas are broadly supported by the other big winner in Sunday's polls, an anti-establishment grouping led by rock star Pawel Kukiz.
"If it turned out that we are a few seats short (of a majority), I would prefer a stable cooperation, and the first natural partner is Mr Kukiz," Jaroslaw Gowin, who leads one of the smaller allied groupings with which PiS fought the election, told Polsat News TV.
"If Kukiz decides otherwise, then we'd have to bet on a scenario of a minority government," said Gowin, who PiS officials say will most likely be the new defense minister.
The latest exit poll by IPSOS, gave PiS 37.7 percent of the vote, translating to 232 seats in the 460-member lower house of parliament. Kukiz was on course to secure around 40 seats.
The final numbers could fall further if a handful of smaller parties exceed vote thresholds for getting into parliament.
Kukiz told Radio Zet he did not plan to enter a coalition, but Polish political commentators assume that Law and Justice will be able to count on at least some of the group's MPs in parliament.
(Reporting by Agnieszka Barteczko and Adrian Krajewski, Writing by Patrick Graham and Wiktor Szary; Editing by Toby Chopra)