Democrat John J. Mangelli held a slim, 68-vote lead in early results over Oyster Bay Republican Supervisor John Venditto, who was seeking his 10th term in office.
Absentee ballots need to be counted.
Mangelli, an attorney, criticized the town's tax hikes and handling of loans, while Venditto had touted his efforts to avoid overdevelopment and protecting local infrastructure.
The town has come under fire for its dealings with indicted restaurateur Harendra Singh. A September federal indictment said that Singh bribed a town official, who was unnamed, in order to receive "indirect guarantees" on debt.
And in March, town Planning and Development Commissioner Frederick P. Ippolito was charged with six counts of federal income tax evasion for allegedly failing to report $2 million of income, most of it from a town contractor. Ippolito pleaded not guilty.
Voters in two other Nassau County towns also headed to the polls Tuesday to elect candidates for supervisor and other council seats.
In the Hempstead race for supervisor, Republican Councilman Anthony Santino was leading Democrat Rita Kestenbaum, who served on the board 15 years ago.
Republican Kate Murray, the incumbent, had been supervisor since 2003. Murray ran for district attorney against Acting District Attorney Madeline Singas, a Democrat.
Santino had claimed that his more than two decades of experience on the board qualified him for the town's top post. Kestenbaum, a gun control activist, has criticized town finances.
North Hempstead Supervisor Judi Bosworth, a first-term Democrat, was leading challenger Anthony Bulzomi, a Republican and school board trustee in Carle Place. Bosworth campaigned on environmental initiatives and promised to continue with reforms to the town's building department.
Bulzomi criticized that department as unfriendly to developers and residents, and he questioned the town's handling of the Yes We Can Community Center in New Cassel.
Glen Cove Mayor Reginald Spinello was seeking a second term, running on the Democrat and Republican lines, against Councilman Anthony Gallo, a Republican running with the Glen Cove United Party. Gallo lost to Spinello in a September Republican primary.
Gallo said he would work to boost the city's economy and cut down on overdevelopment, while Spinello said he wanted to finish initiatives begun in his first term, which include efforts to revitalize the waterfront with housing and new businesses.
In Long Beach, seven candidates vied for three seats, and in Glen Cove, 18 candidates were seeking six seats. In Hempstead, Oyster Bay, and North Hempstead, three council seats each were up for grabs.
Hempstead and Oyster Bay had elections for town clerk, and the receiver of taxes position was up in all three Nassau towns.