The opposition complained that 3m extra ballot papers had been printed, raising fears that they might be used to stuff ballots at remote polling stations.
Some Senate Republicans, worried that their seats are vulnerable, are hoping to gain the endorsement of the Working Families Party, which would give them an extra ballot line.
Steven H. Richman, a lawyer for the City Board of Elections, then sealed the extra ballot in a manila envelope and tucked it away.
According to several people with knowledge of the events, senior PNU officials began to worry after the count in Nairobi's Kamukunji constituency was cancelled because of allegations about extra ballot papers.
The vote between the interim AFA president Luis Segura and the entrepreneur and television personality Marcelo Tinelli was postponed with no new date set after organisers found an extra ballot had been cast in a 38-38 tie.
Officials at the Foundation for Democratic Process, a local group that is monitoring the election, said they were hearing reports of extra ballot boxes mysteriously appearing after the counting was nearly completed in some districts.
