Belgrade (dpa) - The chief of the Croatia‘s most powerful party resigned Tuesday in the wake of a corruption affair and the collapse of the government coalition."I resign the post of the HDZ president," said Democratic Union chief Tomislav Karamarko in a press conference after he failed to form a new government in the wake of the collapse of the last regime. "I promised a majority in parliament and did not make it."Karamarko‘s HDZ was the dominant party in a coalition that emerged after November 2105 elections. However, the alliance with a small newcomer party, the Most (Bridge), fell apart amid demands for Karamarko to step down as deputy premier because of corruption allegations.A government corruption watchdog had earlier ruled that the allegations stand and that Karamarko violated the rules by siding with the Hungarian energy concern MOL in its dispute with Croatia over the INA petrol company.After HDZ toppled non-partisan Prime Minister Tihomir Oreskovic earlier this month, Karamarko promised to forge a new government, but failed.The moved on Oreskovic after he had called for Karamarko to step down.Parliament decided Monday to dissolve itself on July 15, paving the way for snap polls in early September.The conservative HDZ won all but three parliamentary elections since Croatia split from former Yugoslavia 25 years ago this week.It also won the polls in November, but only marginally, after losing a huge lead in popularity, which critics attributed to Karamarko‘s mismanagement.