While the Agency will only confirm that their agents "are in the New Brunswick area," multiple sources tell NBCNewYork that the probe has the potential to reach not only into City Hall, but also deep inside the New Brunswick Police Department.
In addition, investigators appear to be curious about an election fraud investigation earlier this year by the Middlesex County Prosecutor's office.
According to sources, several Rutgers students who were part of a "reform" election a year ago that sponsored a referendum that would have elected the city's councilmen by wards, instead of the existing at-large system.
The reformers lost by slightly over 80 votes, but their attorney said they claimed to the FBI that the County Prosecutor appeared to be investigating them instead of City Hall.
The police department is not believed to be a 'target' at this time.
But it appeared the feds are interested in a pattern of donations made by police officers to Mayor James Cahill's re-election campaign earlier this year.
The current investigation is focused on the use of absentee ballots in the Mayor's primary campaign against local attorney Patricia Bombelyn.
The mayor's aide, Kevin Jones, was caught on camera before the primary in a city park with a stack of absentee ballots.
However, according to reports at the time, Jones was not authorized to carry or distribute those absentees, as required by state election law.
No arrests were expected Tuesday, but FBI agents were serving subpoenas at the Middlesex County Clerk's office and at the County Board of Elections office.