Budka said the decision of the PO board was unanimous.
Budka praised Kidawa-Blonska for her determination in opposing the ruling party's plans to go ahead with the election on May 10 under a government-modified format due to the coronavirus epidemic, which Budka said would be "bad, unfair and dangerous."
At the last moment, the election was postponed by Jaroslaw Kaczynski, leader of the ruling party Law and Justice (PiS), and Jaroslaw Gowin, who heads PiS's junior coalition partner Agreement.
Budka said Trzaskowski's candidacy will now be presented to PO's partners within the broader Civic Coalition (KO) bloc. (PAP)