WARSAW (Reuters) - Public support for Poland's largest opposition party, the centrist Civic Platform (PO), has exceeded that of ruling right-wing Law and Justice (PiS) party for the first time in two years, an opinion poll showed on Wednesday.
The survey by Kantar Millward Brown (KMB) showed 31 percent of respondents would vote for PO if elections took place on Sunday, a rise of 4 percentage points compared to the previous poll on March 30.
Support for the eurosceptic PiS remained stable at 29 percent, while backing for the pro-business Nowoczesna party fell by three percentage points to 5 percent, the level of the election threshold.
Support for the rightist, anti-establishment grouping Kukiz'15 stood unchanged at 10 percent.
"For sure one can see a trend that Civic Platform is taking over the electorate of Nowoczesna," said Wojciech Holdakowski, who is responsible for Polish political polls at KMB. "Support for PiS seems in a slightly declining trend."
The poll follows a slew of surveys suggesting that most Poles did not support the government's attempts last month to block the re-appointment of former Polish prime minister Donald Tusk as head of the European Council. Tusk is a former PO leader and arch rival of PiS head Jaroslaw Kaczynski.
The European Commission has accused the PiS government of undermining democracy with its overhaul of the constitutional court. The party is currently planning to shake up the judicial system, a move sharply criticised by rights groups.
The Nowoczesna party, which had support of more than 20 percent at the start of 2016, has suffered from leaked photos of its leader who was spotted on a plane to a holiday destination during an occupation of parliament by the party's lawmakers.
Holdakowski also said that while PO, which lost the 2015 election to PiS, has managed to regain support in the past few months, support for the Kukiz'15 grouping also rose, signalling that combined support for right-wing parties remains high.
The Kukiz'15 grouping is a diverse coalition of ultra- nationalists, eurosceptics, libertarians and proponents of electoral reform, led by a 53-year-old rock singer Pawel Kukiz.
The next parliamentary election is not due until 2019, but Poles will vote next year in regional elections.
(Reporting by Marcin Goettig; Editing by Gareth Jones)