(2010–15) Serbia's electoral system was reformed in 2011, such that parliamentary mandates were awarded in numerical order to candidates on successful lists. Mladenović received the forty-fourth position on the DSS's electoral list in the 2012 Serbian parliamentary election. The list won twenty-one mandates, and he was not elected. He received the second position on the DSS's list in the concurrent 2012 Belgrade city election, and was re-elected when the list won ten mandates. The DS and Socialists initially maintained their municipal coalition agreement following the election, and the DSS again served in opposition. In late 2013, the party participated in a key vote of non-confidence that forced the resignation of mayor Dragan Đilas. The government of Serbia dissolved the Belgrade assembly in November 2013 pending new elections, and Mladenović was appointed to the city's provisional authority. Mladenović was promoted to the tenth position on the DSS's list in the 2014 Serbian parliamentary election, in which the party failed to cross the electoral threshold to win representation in the assembly. He again received the second position on the party's list for the Belgrade assembly in the concurrent 2014 city election and was re-elected when the list won nine mandates. The Progressive Party won a majority in the municipal elections, and Siniša Mali became the city's new mayor. On Mali's proposal, Mladenović was elected by the assembly as the city's deputy mayor. Independent Democratic Party of Serbia Mladenović and six other DSS members of the Belgrade assembly were expelled from the party in July 2015 by leader Sanda Rašković Ivić, on the grounds that they were attempting to turn the DSS into a satellite of Aleksandar Vučić's Progressive Party. Mladenović subsequently created a breakaway party called the Independent Democratic Party of Serbia and entered into negotiations with the Progressives for an alliance at both the republic level and in Belgrade. He was included in the tenth position on the Progressive Party's coalition list in the 2016 Serbian parliamentary election and was elected to the assembly when the list won a majority victory with 131 out of 250 mandates. His term in this office was brief; he could not hold a dual mandate as a member of the National Assembly and deputy mayor of Belgrade, and he resigned his seat on 3 October 2016. He was the party's sole representative in the National Assembly during this time and appears to have been its