He was a member of Sligo Borough Council (formerly Sligo Corporation) from 1999 to 2014, having been elected on three occasions, and was a member of
Sligo County Council from 2017 to 2020. He was co-opted in March 2017 to replace his father Seán MacManus, and retained the seat at the
2019 Sligo County Council election. He contested the
2016 general election in
Sligo–Leitrim and was the last candidate to be eliminated. MEP
Matt Carthy was elected as a
TD for the
Cavan–Monaghan constituency at the
2020 general election. MacManus was nominated to replace him in the
European Parliament. MacManus sat on the Agriculture and Rural Development Committee where he advocated on behalf of small Irish family farmers, and highlighted the lack of investment in the west of Ireland, and campaigned to have the Western Rail Corridor opened. He was also a member of the Committee on Economic and Monetary Affairs in addition to the EU Delegations for relations with South Africa and with Palestine. He lost his seat at the
2024 European Parliament election following a poor campaign by Sinn Féin in both those and the
2024 Irish local elections held on the same day. MacManus was also an unsuccessful candidate in
Sligo–Leitrim at the
2024 general election, again being the last candidate eliminated, despite outpolling TD
Marian Harkin on the first count. He currently serves as chairperson of County Sligo Sinn Féin having been selected by its members. ==References==