Nešić co-founded the local party New Strength (Nova Snaga) in Kragujevac in 2014 and was recognized as its leader.[2] New Strength contested the 2016 local election in Kragujevac on the electoral list of Boris Tadić's Social Democratic Party (SDS), and Nešić appeared in the seventh list position.[3] The list won six seats, and he was not immediately elected.[4] He received a mandate on 6 June 2016 as the replacement for another candidate.[5] Some SDS delegates left the party soon after the election to join the governing coalition led by the rival Serbian Progressive Party (SNS). Nešić wrote unfavourably of this situation, and of his experience working with the SDS generally, in an article published the following year.[6]
New Strength contested the 2020 Serbian local elections in Kragujevac on an independent coalition list called Alternativa. Nešić received the second position on the list and was re-elected when it won four mandates.[7]
In June 2021, New Strength collectively joined "Action" (Akcija), a citizens' initiative established by the party Together for Serbia (ZZS).[8] The following month, New Strength joined Together for Serbia outright.[9]
Together for Serbia and "Action" contested the 2022 Serbian parliamentary election as part of the We Must (Moramo) coalition. Nešić was awarded the fifth position on the coalition's electoral list and was elected when it won thirteen mandates.[10][11] Shortly after the vote, Together for Serbia and "Action" merged into a new party called Together (Zajedno!).[12] The SNS and its allies won the election, and Nešić served as a member of the opposition.
During his parliamentary term, Nešić was a member of the spatial planning committee,[a] a deputy member of the economy committee,[b] a deputy member of Serbia's delegation to the Parliamentary Assembly of the Mediterranean, and a member of thirty-six parliamentary friendship groups.[c][13]
He was not a candidate in the 2023 Serbian parliamentary election, and his term ended when the new assembly convened in early 2024.
In the 2023 Serbian local elections, Nešić led a coalition list in Kragujevac of Together, Serbia Centre (SRCE), Ecological Uprising (EU), the Green–Left Front (ZLF), and Šumadija Region.[14] He was elected to a third term when the list won six seats.[15] The SNS and its allies won the election, and he now serves in opposition as the leader of the New Strength KG–Together, Šumadija Region assembly group.[16]
He strongly criticized the city's development strategy in May 2024, accusing the governing coalition of squandering an important opportunity by bringing forward a document filled with errors and illogical proposals.[17]