According to Ipsos, PiS is expected to win 36.6% of the vote, with 31% for the centrist opposition.

The Civic Coalition of Donald Tusk has a better chance of forming a coalition if that is true.

Under Jaroslaw Kaczynski’s leadership, the PiS has ruled for eight years.

A PiS leader admitted he did not know if the party’s “success” would translate into another term in power.

The initial results place PiS in the lead, but they reflect strongholds in small towns and the countryside. On Monday morning, Ipsos published a follow-up poll to its Sunday evening poll.

In what seemed like a victory rally in Warsaw, Mr Tusk, 66, told a large crowd of jubilant supporters that Poland had won and democracy had triumphed. It is the end of the bad times, the end of the PiS government.”

As the Ipsos poll flashed up on the screen and Mr Tusk appeared to loud cheers and chants, there were roars.

Turnout was probably 72.9%, the highest since 1989, according to election officials.

Although polls closed at 21:00 local time, there were still queues of voters reported late into the night in Warsaw and Krakow, and early into the morning in Wroclaw.

Ipsos reports that more 18-29 year olds voted than over-60s.

According to a later poll, PiS was headed for 198 seats in the 460-seat Sejm, falling short of the 231 needed for a majority. Despite a predicted 14 seats, it is unlikely to get much support from the far-right Confederation party.