The Nationals have now lost 11 of their last 12 games, as their record fell to 4-11.
Mets right-hander John Maine pitched 6 2/3 innings, giving up two runs on five hits. In the first inning, Ryan Zimmerman hit a sacrifice fly to drive in Cristian Guzman and give the Nationals a 1-0 lead. Three innings later, Kearns broke a 1-1 tie with a solo home run.
Washington then had numerous opportunities to score against Maine, but ended up going 0-for-7 with runners in scoring position.
"I thought we were going to score a little bit more runs," Acta said, "but we wasted opportunities again."
In the first inning, for example, the Nationals had runners on first and second with one out, but both Milledge and Kearns flied out to right fielder Ryan Church to end the threat.
In the third, Belliard had a one-out double. He ended up staying at second base after Zimmerman and Nick Johnson ended the threat by striking out.
Maine was able to get two quick outs in the seventh, but Guzman and Belliard walked. Mets manager Willie Randolph took Maine out of the game and put in reliever Joe Smith, who struck out Zimmerman to end the threat.
"We've had our chances all year," Zimmerman said. "We just need to have one game where someone steps up and get some hits, and it will come. Smith is tough. He had sinkers and sliders. He made a good pitch to strike me out. You have to give them credit sometimes. It's frustrating, but we have to keep going, keep trying and keep working. That's all you can do. It will turn around."
Left-hander Matt Chico started for the Nationals and admitted that he didn't feel right once he stepped on the mound in the first inning. He was rushing to throw his pitches, and couldn't find a happy medium when he was on the mound.
"I didn't trust my stuff," Chico said. "It's plain and simple."
Not trusting his stuff proved to be costly for Chico, as he gave up three home runs in the game. The Nationals were ahead, 1-0, when he gave up a solo home run to Church in the bottom of the first inning.
The biggest blows came in the fifth inning. The Nationals had a 2-1 lead when Jose Reyes tied the score with a solo shot. Three batters later, Carlos Beltran hit Chico's first pitch -- a changeup -- for a three-run home run.
"I just didn't execute my pitches," Chico said. "I was just fighting to hit the zone and hit my spots. If I wanted a fastball in, I would throw it down the middle. I got away with quite a bit, but the ones that hurt were home runs and [resulted in] five runs."
Lack of pitching and timely hitting -- put those two together, and one comes up with a tough loss for the Nationals.