Sen. Antoine Thompson, D-Buffalo, is trailing Republican opponent Mark Grisanti by 598 votes, said GOP spokesman Scott Reif.
The Thompson race is one of three undecided races around the state whose outcome will determine the majority of the state Senate.
Sen. Suzi Oppenheimer, D-Mamaroneck, Westchester County, had a 180-vote advantage over challenger Bob Cohen, with about 80 percent of precincts reporting on Wednesday. An updated in that race is expected later today.
Sen. Craig Johnson, a Long Island Democrat, trails his Republican opponent Jack Martins by several hundred votes.
Democrats need to win all three races to keep control of the Senate. They currently have a 32-29 majority with one vacancy. If Democrats win two of three, the Senate is tied 31-31.
Democratic spokesman Austin Shafran noted that thousands of absentee ballots and emergency ballots remain to be counted.
“Ballots are still being counted in the three outstanding races, but once every vote has been counted it will be clear, Democrats retained the majority,” he said.