The administration of Poland's Law and Justice (PiS) claimed victory in Sunday's general election.
Its main rival, the central Civic Coalition (KO), holds 27.4%.
PiS was at loggerheads with the EU on Polish judicial reforms and was also criticized for its position on gay rights.
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"We have success," jubilant PiS leader Jaroslaw Kaczynski told the supporter of the party headquarters in Warsaw.
"We have four years of hard work. Poland needs to change and it must change for the better." 19659014] copyright
If the exit poll proves accurate, calculations by TVN's private broadcaster suggest that the PiS can hold 239 MP in the 460-seat lower house.
By the same calculation, the KO would take 130 seats and the left-wing coalition Lewica, in third place, 43 seats. Turnout is over 60%, the exit poll suggests.
Lewica also celebrates its predicted result after the left-wing parties lost four years ago due to fragmentation. Robert Biedroń, one of the bloc's three co-leaders and Poland's first open source lawmaker, said at a rally: "We are back in parliament. We will return to where the Polish left has always belonged."
The first official results are expected later on Monday.
LGBT rights became the single biggest cultural issue before the election. PiS – and the Roman Catholic Church – maintain that gay rights are a threat to traditional Polish families and values.
years ago the EU ordered Poland to halt the application of a new law that critics said would give the PiS political Supreme Court control.
The governing party argued that reforms were necessary to remove judges appointed during the communist era and to make the court more efficient.
But the European Commission – the EU's executive arm – argued that the reforms would reduce the rule of law by giving the party control over the judiciary.