Leicester South voters face four ballots in one day
About 400 people will be hired to count ballots in Leicester on 5 May as voters face four ballots on the same day.
Constituents in Leicester South will vote in a parliamentary by-election, mayoral and city council elections and the alternate vote referendum.
Leicester returning officer Perry Holmes said 500 people will help at polling stations and 400 at the count.
"It will be a challenge to us - we have 230,000 on our register," Mr Holmes said.
"When you multiply that by the number of ballots they have on that day - it is a lot of paper to move in a short space of time."
Former MP Parmjit Singh Gill is running for the Liberal Democrats in the Leicester South by-election along with Labour candidate Jonathan Ashworth, who is Labour leader Ed Miliband's head of party relations.
Mr Gill was Leicester South MP from 2004 to 2005, having gained the seat from Labour in the 2004 by-election.
The seat is vacant after sitting Labour MP Sir Peter Soulsby stepped down to run in the city's first mayoral election.
The Conservatives have not yet chosen a candidate for the vacant MP seat.
City councillor Ross Grant is running for the Conservatives in the mayoral election. Nominations for that election close on 4 April.
The new mayor will have the power to initiate policies across council services, and will select up to nine councillors as a supporting cabinet.