A resident of Kragujevac, he was for many years a close ally of longtime mayor Veroljub Stevanović and a member of the latter's Together for Šumadija (Zajedno za Šumadiju) party.
At the republic level, both Stevanović and Milenić were initially members of the Serbian Renewal Movement (Srpski pokret obnove, SPO).
[5] From 2000 to 2011, parliamentary mandates in Serbia were awarded at the discretion of the sponsoring parties and coalitions, and it was common practice for seats to be assigned out of numerical order; the SPO could have selected Milenić as a member of its assembly delegation, but it ultimately did not.
[6] The SPO experienced a serious split in 2005, and both Stevanović and Milenić joined a breakaway group called the Serbian Democratic Renewal Movement (Srpski Demokratski Pokret Obnove, SDPO).
[10] This alliance participated in the 2008 Serbian parliamentary election as part of the For a European Serbia list led by the Democratic Party (Demokratska stranka, DS).
[16] Both Stevanović and Milenić resigned from the national assembly in September 2011, due to a determination that changes in Serbian law had made their functions in government at the municipal level incompatible with serving in the legislature.
[17] (It was later clarified that serving as president of a local assembly did not create a conflict of interest and that parliamentarians could hold this role on a concurrent basis.)
Serbia's electoral laws were changed in 2011, such that mandates were awarded to candidates on successful lists in numerical order.
[19][20] He was selected for another term as president of the assembly and served in this role until 2014, when the Serbian Progressive Party and its allies ousted Stevanović as mayor and formed a new local administration.
[28][29] In August 2019, he argued that the PSG's decision on boycotting the next Serbian parliamentary election should be made openly by the entire party rather than by its leadership alone.