The Democrats have made major gains here on Long Island over the past 10-15 years. Long Island was once staunchly Republican, most of the elections in recent years on a national, and local level have gone to the Democrats. Long Island hasn't gone Republican on the Presidential level since 1988, 4 of the 5 Congressman on Long Island are Democrats, both Nassau & Suffolk have Democratic Executives, Democratic controlled Legsilatures and a Democratic DA. Albeit a shrinking one the GOP still had a registration advantage, well now in Nassau that registration advantage is gone.
http://www.newsday.com/news/local/nassau/ny-podem0912044315oct09,0,6578926.story