Poland’s ruling Law and Justice party (PiS) has suffered a loss in a mayoral race in the city of Rzeszow.
Konrad Fijolek, a candidate supported jointly by opposition parties, won a landslide victory with a 56 per cent vote share, avoiding a run-off poll.
The candidate from PiS, Ewa Leniart, received nearly 24 per cent.
The result may come as a surprise given that Rzeszow is the capital of the southeastern province of Podkarpackie, a highly conservative region where PiS has done well in the past.
The mayoral election could be an indication of how strong the party’s support is after nearly six years of governing the country.
The next general election in Poland is scheduled for 2023, but there has been speculation recently about the possibility of early elections due to friction within the right-wing coalition.
The leader of a small party in the coalition, Jaroslaw Gowin, called the results a warning for the government.
"Attacking the middle class, raising taxes, centralism instead of self-governance, and disrespecting coalition partners are paving the way for the opposition to take power," Gowin wrote on Twitter.
The result was also hailed by opposition politicians, who saw it as an encouraging sign that they stand a chance of defeating PiSin the future if they manage to unite.
"All the opposition parties, side by side, supported this candidate, giving such enormous energy from the very beginning," Cezary Tomczyk, a lawmaker with the centrist opposition party Civic Platform, told Polsat News.
"When we said that unification made sense, we showed it with examples like these."
Tomczyk said the victory in Rzeszow was the most important victory for the opposition since the socially liberal politician Rafal Trzaskowski won the election to be mayor of Warsaw, the capital, in 2018.
Law and Justice, popular for its welfare spending in Poland, plans even more spending and higher taxes on those with higher incomes.