In one of the nation’s tightest, undecided congressional races, incumbent Long Island Rep. Tim Bishop is clinging to a thin lead over his Republican challenger.

A spokesman for Bishop said that with an initial count of absentee ballots complete, the Democrat now has a 235-vote edge over opponent Randy Altschuler. The Altschuler campaign acknowledged the lead, but said it was only 234 votes.

Suffolk County election officials have not released a formal tally.