[1] Before becoming government minister he served one term as MP in the 6th Sabor from 2007 to 2011 where he chaired the parliamentary committee for internal affairs and national security.

[1] During this time he also ran for mayor of Split in the 2009 local elections but finished runner-up with 34.7 percent of the vote, behind independent Željko Kerum.

[2] The final months of Ostojić's term as Minister of the Interior was marked by the 2015 European migrant crisis, causing an inflow of over 39,000 migrants into Croatia from Serbia by 22 September 2015,[3] after the construction of the border fence on the Serbia-Hungary border.

Many migrants fled the Syrian Civil War, as well as poor economic conditions in Africa and South Asia, with Croatia serving mainly as a transit country towards Germany, Scandinavia and Western Europe.

[4] The villages of Tovarnik, Ilača and Opatovac, as well as the city of Beli Manastir served as the main acceptance centers for migrants in eastern Croatia, while 1,200 were also housed at Zagreb Fair.