By virtue of its performance in the 2003 parliamentary election, the DSS had the right to appoint twenty delegates to the Assembly of Serbia and Montenegro in early 2004.
Gajić was included in her party's delegation and served on the federal assembly's committee for internal economic affairs and finance.
[7] Serbia's electoral system was reformed in 2011, such that all parliamentary mandates were awarded to candidates on successful lists in numerical order.
[14] The DSS experienced a serious split in late 2016, after which Gajić, Milan Lapčević, and Dejan Šulkić were the only assembly members who remained with the party.
In 2019, Gajić criticized the parties of the opposition Alliance for Serbia for boycotting the assembly, describing their decision as rushed and ultimately counterproductive.
[16] The DSS created a new alliance called METLA 2020 for the 2020 Serbian parliamentary election, and Gajić appeared in the third position on its list.
The following year, the DSS and the Movement for the Restoration of the Kingdom of Serbia (POKS) formed a coalition called the National Democratic Alternative (NADA).
[26][27] In the 2020 Serbian local elections, she was re-elected to the municipal assembly on the list of an alliance called "Only Forward Svilajnac," which won two seats.