Three players had one RBI each, and three had two hits for the Nationals, who have won five of their last six games.
Chico improved to 7-9, and closer Chad Cordero earned his 37th save this season.
Six players had one hit each for the Phillies, who have won seven of their last 10 games -- but, with the loss Saturday, fell into a tie for first place in the NL East with the Mets. New York beat Florida, 13-0, Saturday afternoon.
The losing pitcher was starter Adam Eaton (10-10).
2014: NFL Cheerleaders [PHOTOS]
LeBron James reveals his new Nike shoes