Cecilia Tkaczyk, a farmer from rural Duanesburg, overcame a 35-vote deficit to beat George Amedore, a homebuilder from Rotterdam, to represent the state's new 46th Senate District -- a district many Democrats said was created to ensure Amedore's victory.
She is the last winner in the country of a state legislative race held in November.
Her victory Friday, the second-closest in modern state Senate history, gives Democrats a 33-30 Senate majority, although the chamber, which began its new legislative session Jan. 9, is controlled by a power-sharing coalition of Republicans and a breakaway conference of six independent Democrats.
Amedore -- who filed his oath of office as a senator Jan. 3 after being certified the winner by a state judge Dec. 19 -- said through a spokesman he would not challenge Tkaczyk's win.
The former state assemblyman holds the record as the shortest-tenured state senator in modern Senate history, the Albany Times Union said.
"No one believed our campaign had a chance in a district hand-carved by Republicans, and yet the power of good ideas and a strong campaign proved itself," Tkaczyk said in a statement Friday.
Senate Republicans said in a statement "the outcome of this race doesn't change anything" in terms of Senate control.
After acting state Supreme Court Justice Guy Tomlinson's certified Amedore's victory, Tkaczyk's campaign appealed. Tomlinson had said Amedore won by 37 votes out of more than 126,000 ballots cast Nov. 6.
The state Supreme Court, despite its name, is a trial-level court in New York.
A mid-level court ruled 99 more ballots must be opened. Amedore lost an appeal of that ruling to the state highest court.
Tkaczyk closed the gap Thursday after eight previously challenged paper ballots in Greene County were counted. She sealed her victory Friday when she got 69 of 90 paper-ballot votes counted in Ulster County. A remaining ballot in Albany County went to Amedore.