The Nationals' losing streak is the longest they've had since dropping that many from June 23 to July 4, 1991, when they were known as the Montreal Expos.
If the Nationals' streak grows to 12 games on Wednesday night, they will tie the Royals for the longest losing streak in the Major Leagues this season.
"Everything's going bad for us right now," left fielder Willie Harris said. "I don't know why. I don't understand it."
Harris provided a first-inning spark for Washington's offense when he smacked a Blanton fastball into the right-field seats. The Nationals' sharp hitting continued in the fourth inning, when three consecutive base hits by Lastings Milledge, Ronnie Belliard and Jesus Flores led to another run.
Belliard knocked in the Nats' fourth run of the game with another base hit in the fifth. The shortstop had a season-high four hits on Tuesday and is hitting .632 (12-for-19) in his last five games.
"He's been tremendous," manager Manny Acta said. "He's a guy we can't take out of the lineup right now."
But in the bottom of the fifth, some of the same problems that have plagued Washington during the previous 10 games began to surface.
Shane Victorino led off the inning with a triple. Greg Dobbs followed with a fly ball to left field, which bounced off Harris' glove, allowing Victorino to race home.
"I ran in, the ball hit me on the heel of my glove and I didn't make the play," Harris said.
Two batters later, the Phils cut the Nats' lead to one run when Geoff Jenkins lofted a sacrifice fly to left field.
Bergmann rebounded nicely on Tuesday from his six-run, three-inning outing against the Mets last week. This time, the right-hander held the Phillies to four runs -- three earned -- in 6 1/3 innings.
The hurler had a chance to help himself at the plate and give Washington some insurance runs in the sixth inning, when he came up with runners on first and second and nobody out. He laid down a bunt that was scooped by Phils reliever Chad Durbin, who threw out the lead runner at third base. Durbin then retired the next two hitters to end the threat.
"That dude is filthy, man," Harris said of Durbin.
"We had the lead, and [Bergmann] was pitching very good, and we thought we had a good chance today to snap out of it and then couldn't make a couple of plays out there that really hurt us," Acta said.