By Gareth Jones
WARSAW, Oct 6 (Reuters) - Poles look set to hand Prime Minister Donald Tusk's centrist Civic Platform (PO) four more years in power in Sunday's election, opting for political stability, closer EU ties and cautious economic reforms at a time of European crisis.
PO's main rival, the nationalist-minded Law and Justice party (PiS), has waged a feisty campaign and narrowed the gap in opinion polls, but its abrasive leader Jaroslaw Kaczynski would struggle to find coalition partners even if he won.
A rogue card in the election is Janusz Palikot, a wealthy businessman and former PO lawmaker whose libertarian new party may lure some younger urban voters from PO with its attacks on the powerful Catholic Church and support for gay rights, abortion and legalisation of soft drugs.
The combination of a reinvigorated PiS and Palikot's poaching of protest votes could erode support for PO, forcing it into an unwieldy three-party coalition, possibly including the post-communist left, that might slow economic reforms.
Ratings agencies have said they may downgrade Poland if the new government does not act swiftly to curb a budget deficit expected to reach 5.6 percent of gross domestic product (GDP) this year and to rein in public debt.
Tusk, rated by voters as "the most trustworthy" of the party leaders, has campaigned on Poland's record of strong economic growth, including during the 2008-09 global crisis, and says this would be put in jeopardy if PO loses.
Tusk, whose country currently holds the EU's rotating presidency, also stresses his close personal ties with leaders such as German Chancellor Angela Merkel. PO, unlike PiS, wants Poland to join the euro once the euro zone overcomes its sovereign debt crisis.
"These are serious elections... After four years as the prime minister who protected his country against the first wave of the crisis I have a duty to say that everybody now expects an even more powerful wave," Tusk told a rally in Krakow.
"In these elections, PO must strive with all determination and conviction because it provides a guarantee of stable, responsible government."
Many voters will back PO not out of support for its policies but out of the memory of PiS's last stint in power in 2005-07, which was marred by disputes with social groups from doctors to prosecutors, attempts to purge officials linked to the communist past and strained ties with the EU and Russia.
"I am not in love with PO but they do at least guarantee that I can live in a normal country," Adam Michnik, renowned communist-era dissident and now editor of Poland's leading liberal daily Gazeta Wyborcza, told Reuters.
"Tusk is a rational leader. Of course he can be a bit populist, as when he called for the castration of pedophiles, but he is rational. And Poland is stable and safe. When Kaczynski governed, I was scared just to turn on the TV."
To his supporters, Kaczynski is an honest patriot and good Catholic who will defend Poland against what they see as a godless EU, historic foes Germany and Russia and unscrupulous foreign capitalists they say buy up Polish assets on the cheap.
PiS wants to halt many privatisations, increase social spending and slap a tax on financial transactions.
Kaczynski raised eyebrows in Germany this week by repeating in a new book his view that Berlin is trying to subdue Poland. As prime minister in 2007 he almost scuppered a deal on a new EU treaty by invoking the number of Poles killed by the Nazis in World War Two to press his demand for greater voting rights.
Compounding the toxic acrimony of Polish politics, Kaczynski accuses Tusk's government and Russia of causing -- by criminal neglect or by malicious design -- the death of his twin brother, Polish President Lech Kaczynski, last year.
President Kaczynski died with 95 others, including many senior PiS officials, when their plane crashed in thick fog near Smolensk in western Russia. They had been planning to mark the 70th anniversary of the massacre of Polish officers by Soviet forces -- an emotional touchstone for all Poles.
Jaroslaw Kaczynski, who still wears only black ties in memory of his twin, has not spoken much of the crash during the election campaign, aware that many Poles want to move on from the tragedy, but that could change if he returns to power.
"Kaczynski is mostly interested in the past, in settling accounts," Aleksander Smolar, a political analyst at the Batory Foundation, told Gazeta Wyborcza on Thursday.
"If he became prime minister he would seek revenge on those he believes are responsible for the Smolensk crash." (Additional reporting by Gabriela Baczynska, writing by Gareth Jones; Editing by Myra MacDonald)