WASHINGTON — Brian Schneider homered against his former team again and Carlos Delgado also went deep to help the New York Mets beat the Washington Nationals 9-3 on Thursday night, finishing a three-game sweep.

Oliver Perez (9-7) handed a 5-3 lead over to the Mets’ beleaguered bullpen in the seventh, and Joe Smith, Duaner Sanchez and Aaron Heilman combined to throw 2 1-3 scoreless innings. Perez allowed six hits, walked three and struck out eight.

The win gave the Mets a half-game lead in the NL East over Philadelphia, which was at Los Angeles on Thursday night.

Washington has lost seven straight.

Schneider, the former Nationals catcher, hit a two-run drive off Collin Balester (2-5) in the fifth to give the Mets a 4-0 lead. It was his first homer since May 14, also against Washington.

Delgado connected for his 26th homer in the sixth, and also drove in a run with a groundout in the fourth.

Washington chased Perez during a three-run seventh. Pinch-hitter Pete Orr hit a two-run triple and scored on Emilio Bonifacio’s bunt single. Bonifacio had been mired in a 1-for-27 slump.

Smith entered after Bonifacio’s hit and retired Ronnie Belliard on a flyball to right to end the inning. Smith and Sanchez combined to work the eighth before Aaron Heilman got the final three outs.

Damion Easley gave the Mets some insurance in the ninth with a pinch-hit, two-run single. New York added two more on second baseman Bonifacio’s throwing error. Lastings Milledge went 0-for-3 with a walk for Washington, ending his career-best 14-game hitting streak.

Notes: SS Cristian Guzman (thumb) and C Jesus Flores (stomach virus) were scratched from Washington’s lineup. … The Nationals activated INF Aaron Boone from the disabled list and placed SS Alberto Gonzalez on the DL. … Mets 3B David Wright made an unusual out to end the fifth when a fan reached out and blocked RF Austin Kearns from catching a ball in foul territory. The umpires called Wright out on fan interference.