The uncertainty surrounds gubernatorial ballots that were not segregated in their state-designated envelope when sent in with the Senate ballots.
Coleman criticized Gov. Christie for scheduling a $24 million special election for Wednesday to fill the seat opened when Sen. Frank R. Lautenberg died. She said, residents could have cast votes for both races in November, just weeks away. She said the scheduling confused many voters.
Buono, who is seeking to unseat Christie, is trailing significantly in the polls. She did not participate in Thursday's conference call, and a campaign worker said the senator was not available for comment.
In her conference call, Coleman, a Democrat whose district covers Mercer and Hunterdon Counties, said she was told by Buono campaign workers that the Attorney General's Office had advised election officials in several counties that the votes could not be counted. Coleman warned that a court battle could ensue.
Coleman said Thursday that she did not know how many votes were involved and that information had to come from each of the state's 21 counties. Whether it is 500 votes or 50, she said, it shows that voters were confused by ballots that arrived in the mail back to back.
The attorney general's statement said, "Based on information received from other counties, we are aware of only a few additional occurrences statewide."
Election officials in Camden, Burlington, and Gloucester Counties said the problem did not appear to be big. They said about six such ballots were received in Camden County, six in Burlington County, and two in Gloucester County.
Election officials also said instructions were sent to voters about using the correct envelopes, which were of different colors.
"People are going to be disenfranchised," Coleman said during her conference call.
In the Senate race, Democratic Newark Mayor Cory Booker defeated Republican Steve Lonegan by more than 10 percentage points. Democrats have alleged that Christie did not want his name on the same ballot as the Senate candidates.
Christie "feared having Lonegan at the top of his ticket," Coleman said, "and he feared having Booker at the top of our ballot."