Long Island voters are heading to the polls today to pick a county executive in Nassau, district attorneys in Nassau and Suffolk and all county legislators.

Voting stations opened at 6 a.m. in both counties and will remain open until 9 p.m. tonight.

The biggest local races are in Nassau, where County Executive Thomas Suozzi, a Democrat, faces a challenge from Republican Edward Mangano and Conservative Steven Hansen. Republican Joy Watson is seeking to unseat District Attorney Kathleen Rice , a Democrat.

>>PHOTOS: Click here to see the latest photos of voters and politicians at the polls

>>MORE: Click to see Newsday's voter's guide, with complete candidate profiles

Suffolk DA runs unopposed

In Suffolk, District Attorney Thomas Spota , Sheriff Vincent DeMarco and Treasurer Angie Carpenter are each running unopposed, thanks to a four-party cross-endorsement deal. Nassau Comptroller Howard Weitzman , a Democrat, and Republican County Clerk Maureen O'Connell also are seeking re-election.

All 19 Nassau legislators and all 18 Suffolk legislators are up for re-election.