The western New York congressional race between incumbent Republican Chris Collins and Democrat Nate McMurray was too close to call, but the challenger appeared to realize that only after initially conceding.
McMurray is now demanding a recount.
The Democrat addressed supporters shortly after 11 p.m., telling them the effort was "going to come up a little short."
That prompted Collins to declare victory about a half hour later.
But with preliminary returns showing the narrowest of margins for Collins, McMurray issued a statement early Wednesday demanding a recount, saying "the will of the voters must be heard."
Collins is seeking re-election to a fourth term while facing trial in 2020 on federal charges of insider trading. He has pleaded not guilty.
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