Unofficial returns from the Westchester County Board of Elections showed Latimer leading Killian by 66,757 to 53,975 of votes counted.
Killian, a Rye City Council member and deputy mayor, challenged the incumbent Latimer, a former Rye City Council member and Westchester County legislator.
Latimer was a state assemblyman from 2005 until his election as state senator in 2012.
The 37th Senate District includes Bedford, Eastchester, North Castle, Rye, Harrison, Mamaroneck, part of New Rochelle, part of White Plains and part of Yonkers.
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