Kujundzic and Prgomet said the reason for their decision was the fact that they respected traditional values and that seniority was one of them.
"The HDZ needs new leaders. This doesn't mean that there's no room for the old ones, but the order must be different," said Kujundzic.
He said Prgomet and he had extended an invitation to cooperate to Tomislav Karamarko and Domagoj Milosevic, but that they made the cooperation conditional on being presidential candidates.
"For the HDZ to become a victorious party, the members who left disappointed or were expelled must come back," Kujundzic said, adding that neither Karamarko nor Milosevic were capable of bringing them back.