General elections were held in the City of Buenos Aires on 5 July 2015 to elect the Chief of Government (mayor), half of the City Legislature and all 150 members of the communal boards to four-year terms. As no mayoral candidate won a majority in the first round, a runoff was held on 19 July, in which Horacio RodrÃÂguez Larreta, of the governing Republican Proposal (PRO) party, defeated MartÃÂn Lousteau and his Organized Citizen Energy (ECO) coalition to become Chief of Government of Buenos Aires.
Incumbent Chief of Government Mauricio Macri was term-limited, and instead ran a successful presidential campaign in October 2015. The City Legislature remained controlled by the governing Republican Proposal (PRO) party and its coalition, PRO Union.
This was the first election in which the Single Electronic Ballot (Boleta ÃÂnica Electrónica, BUE) voting system was implemented.
The 2011 elections in Buenos Aires had resulted in the re-election of incumbent Chief of Government Mauricio Macri in the second round against FPV candidate Daniel Filmus. Macri's party, Republican Proposal (PRO), also remained the largest force in the City Legislature.
The electoral laws of the City of Buenos Aires determined the local elections could not be held concurrently with the nationwide general election being held the same year. The election was thus set for 5 July 2015, with primaries being held on 26 April 2015.
This was the first election in which the Single Electronic Ballot (Boleta ÃÂnica Electrónica, BUE) voting system was implemented. The use of the new electronic system was subject to controversy and criticism from opposition figures, such as leading candidate MartÃÂn Lousteau, who claimed the system was not secure and transparent enough.