In the aftermath of a parliamentary election held on 8 November 2015 where no party secured enough seats necessary to form government, and the ensuing 76 days of negotiations, Orešković was named as a technocratic non-partisan compromise for the post of prime minister by the Croatian Democratic Union (HDZ) and the coalition Bridge of Independent Lists (Most) on 23 December 2015.

With relations growing acrimonious, HDZ in turn rejected several proposals, including an amendment for reducing benefits of MPs,[1] and the adoption of a new waste management plan.

[6] His professional career began in 1992 in the production of American pharmaceutical company Eli Lilly where he held various functions in the field of finance and international business.

[7] After leaving Eli Lilly in August 2005, he continued his career in the Canadian pharmaceutical company Novopharm (now: Teva Canada), as VP of Business Development, Specialty Products and CFO.

[8][failed verification] Orešković was contacted by the Croatian Democratic Union (HDZ) several months before the 2015 parliamentary elections over a possible minister position in the new government.

[12] Orešković's main tasks were to cut the public debt and bring investors to Croatia that had just emerged from a six-year recession.

His plan included the privatization of non-strategic assets, more investments in tourism, energy and infrastructure, taxation of unused property and increased use of EU funds.

[11][13] His government faced its first political challenge with the resignation of the Minister of Veterans Affairs Mijo Crnoja, only 6 days into his term, on 28 January 2016.

[20] On 22 April, representatives of the Jewish and Serb minorities and an anti-fascist group boycotted the official commemoration for the victims of the Jasenovac concentration camp, in protest to what they said was an inadequate reaction by the authorities to events that "downplayed and revitalized" the crimes of the Ustashe regime.

[21] In June, Orešković and Economy Minister Tomislav Panenić signed contracts for onshore hydrocarbon exploration and exploitation with oil companies including INA and Vermilion Energy, worth €88 million.

A new public procurement bill was adopted by the government, that replaced the lowest price criterion with the economically most favourable offer.

[26] Orešković's cabinet had been plagued by tensions between the two governing parties, HDZ and Most, particularly over the INA, Croatia's national oil company, and the Ministry of the Interior.,[27] which culminated in the conflict of interest affair labeled The Consultant Affair, when it was revealed that Tomislav Karamarko's wife had business contacts with a consultant of the Hungarian oil company MOL which was a party in an arbitration processes with Croatia over INA.

[28][29] On 3 June 2016, in an attempt to find a compromise solution for the growing crisis, Orešković called on both Karamarko and Petrov to resign their positions for the sake of stability of the country.