Poland’s most powerful politician, ruling party leader Jaroslaw Kaczynski, said Wednesday the country's postponed presidential election must be held no later than June 28 to be in line with the national constitution.

Originally scheduled for May 10, the vote was postponed without a new date being set amid questions on whether it could be properly conducted during the pandemic.

Kaczynski was reacting to a proposal by the left-wing opposition for a vote in August, after incumbent President Andrzej Duda's term expires. Duda is seeking reelection, with the ruling right-wing Law and Justice party's backing.

Kaczynski said the government will use all available measures to prevent a postponement past June 28. He said it was the last possible date for the election under the constitution that gives time for all necessary procedures to be met and allows the elected president to be sworn in by Aug. 6, when Duda's term expires.

At stake in the elections is whether an opposition candidate can stand a chance of defeating Duda and chipping at the conservative ruling bloc.