"This is a victory," Bishop told supporters shortly before midnight.
Altschuler conceded just after midnight.
Bishop, who was seeking his sixth term in the eastern Suffolk County district, had called the campaign his toughest. In 2010, he edged Altschuler by 593 votes out of about 202,000 ballots cast.
Altschuler, 41, who co-founded two businesses, spent and raised about $2 million, as did Bishop, 62, a former college provost. But Altschuler benefitted from $3 million in super PAC spending on his behalf.
"My opponent may have had the guys with the big checks, I had the guys with the big hearts," Bishop told supporters shortly before midnight.
Early results had Rep. Steve Israel (D-Huntington) ahead in the 3rd District, which also was redrawn. It now runs primarily along the North Shore as far west as Queens. He was opposed by Stephen A. Labate, 44, a Republican from Deer Park whose career has been in financial planning.
Rep. Carolyn McCarthy (D-Mineola), who was first elected in 1996, had an edge in the 4th District as early results were tallied. She ran on a platform to strengthen the economy, create jobs on Long Island and continue her work on gun control. She was thrust into the public spotlight when her husband, Dennis, was shot and killed in the December 1993 Long Island Rail Road massacre.
McCarthy's opponent in the 4th District race, Francis X. Becker Jr., 59, is in his 16th year as the area's county legislator.
He was opposed by Allan Jennings Jr., 45, a Republican who is a former mortgage banker and New York City councilman.
Meeks led in the first early returns that were reported.