Exit polls from local elections in Poland have suggested the ruling conservative government has suffered a number of setbacks.
PM Jaroslaw Kaczynski said he still had good support
The exit polls showed the year-old coalition, headed by the Law and Justice party, behind in the fight for Warsaw council and other city bodies.
Members of the opposition centre-right Civic Platform were claiming victory.
The key battle for the post of Warsaw mayor looks likely to go to a second round later this month.
Overall turnout was forecast to be low. Three hours before polls closed, fewer than 35% of the 30m voters had cast ballots, the national election commission said.
Poland's Prime Minister Jaroslaw Kaczynski had been hoping for good results for his Law and Justice party to help rebuild a stable parliamentary majority after his governing coalition collapsed in September.
A scandal over a film apparently showing a prime ministerial aide trying to buy an opposition member's support sparked rival street protests in Warsaw last month.
The exit polls suggested the Law and Justice Party had lost the fight for Warsaw city council and was behind in Lodz, Poznan and Krakow.
A Civic Platform leader, Jan Rokita, said: "Friends, it's time to celebrate. We've won."
Kazimierz Marcinkiewicz faces a run-off for Warsaw mayor
Mr Kaczynski admitted there had been some setbacks, but said: "Despite unprecedented attacks, despite all the provocation we've faced, a large section of the population understands why we do what we do and supports us."
The contest for Warsaw mayors pits acting mayor Kazimierz Marcinkiewicz - a former prime minister for the Law and Justice party - against a strong Civic Platform challenger, Hanna Gronkiewicz-Waltz.
Exit polls put them neck-and-neck and the vote is likely to go to a run-off.
The prime minister's twin brother, Lech Kaczynski, was mayor of Warsaw until he was elected Poland's president in October last year.
The first official results are expected on Monday.
The election results have extra significance because the winners will have a say in how billions of euros in new European Union funding are spent.