The party at Nationals Park lasted until the ninth inning Friday night, and then the afterglow of the Washington Nationals clinching a postseason berth ceded to a mess. Hours earlier, Manager Davey Johnson had said he would choose his closer nightly between Drew Storen and Tyler Clippard. This time, he chose Clippard. A victory devolved into base hits and boos, to a loss and, maybe, a clear decision.

Clippard earned the job this summer and did it well, but the ninth inning Friday night and the resulting 4-2 loss to the Milwaukee Brewers may have ended his ninth-inning reign as fall encroaches. Clippard allowed three runs on three hits before he handed the ball to Johnson and walked off the mound, the crowd showering him with both bitter jeers and warm, sympathetic clapping.

As Clippard retreated to the dugout, his ERA since the all-star break stood at 5.64. He has blown four saves in the second half and allowed at least one earned run in five of nine appearances this month. Wednesday, he yielded a game-winning homer in the ninth. He has 32 saves this season, and for three years he has been the Nationals’ most valuable reliever. Now Johnson is entrusting him with some of the most crucial innings in the team’s history, and even he knows he is not right.

“It’s been really bad lately for me,” Clippard said. “I’ve been trying to pinpoint what exactly it is. I’ve been feeling really good physically, which makes it more frustrating. When I feel physically 100 percent, I should be getting outs. I have my whole career. Right now, it’s been pretty bad.”

Clippard’s implosion stood in contrast to Storen’s powerhouse performance Thursday night, when he chucked aspirin tablets at the Los Angeles Dodgers, striking out all three hitters he faced. Storen feeds on the adrenaline of the ninth inning — when working the ninth or later this year, he has allowed no runs in 72 / 3 innings while striking out nine.

Storen became the Nationals’ ironclad closer last year, when he saved 43 games. In the spring he got hurt and underwent elbow surgery. He is healthy now, maybe better than ever.

Still, after the game, Johnson stuck to the same plan he outlined earlier in the day. He will pick between Clippard and Storen, the two housemates at the back end of the bullpen, based on matchups and freshness. Storen will be the closer Saturday, but Johnson hasn’t made Clippard a full-time setup man.

“He’ll be fine,” Johnson said. “That one just got away. One battle. He’s been awfully good.”

Johnson pointed to Clippard’s velocity, still hitting 94 mph, as a sign that he is okay. Clippard, while remaining resolved, admitted he’s not.

“I’m searching right now,” Clippard said. “We’ll get it figured out. I’m not too worried about it. I’m still confident as heck. It hurt tonight. I’m not going to lie to you. It’s not easy.”

Edwin Jackson had set him up with eight dominant innings, ending his start by facing the minimum for the final four innings. Jackson was in line for his 10th win thanks to Adam LaRoche’s two-run homer in the first inning.

“The last few starts, I felt like I haven’t helped the team,” Jackson said. “I just want to try to bounce back. Today was definitely a day that I felt like it was up to me take charge.”

Jackson, the most durable workhorse in the rotation, had thrown 101 pitches after eight innings. Johnson might have stuck with him, but when Jackson’s spot came up in the bottom of the eighth, Johnson pinch-hit for him with Chad Tracy.

And so the ninth, with Storen having pitched two straight days, belonged to Clippard. He allowed a leadoff bunt single to Norichka Aoki, which Johnson deemed the key to the inning — Aoki’s speed forced Clippard to rush and boggled his delivery, Johnson said.

Clippard and catcher Jesus Flores got crossed up in the next at-bat, and when a change-up deflected off Flores’s mitt and rolled to the backstop, Aoki moved to second. “Him to getting to second was big,” Clippard said. “There wasn’t really any doubts I was going to get out of it.”

Rickie Weeks smacked a deep flyball to the warning track in right-center field. Bryce Harper tracked it down, and Aoki scooted to third base. The flyout created a terrifying sight: Ryan Braun walking to the plate with one out and the tying run on third base.

Braun, the reigning MVP and a 40-homer menace, had already doubled twice. Against Clippard, he lashed a high change-up to left field for a single, and Aoki trotted home with the tying run.

Braun then stole second off Clippard, who at his best struggles to keep runners from stealing. “I wasn’t really expecting him to go,” Clippard said. “That’s on me. That’s just absent-mindednes. That can’t happen.”

Usually, he can just strike out the guy at the plate. Currently, he is missing few bats, leaving too many fastballs up. Aramis Ramirez drilled a fastball to the left field corner for a double and Braun scored the winning run easily.

“I’ve been through struggles before in my career, and that’s pretty much the common theme,” Clippard said. “I’m a guy who needs to locate my fastball well, and I haven’t been doing that.”

The Nationals could find solace only in the out-of-town scoreboard. The Atlanta Braves lost in Philadelphia, which reduced the Nationals’ magic number to seven to clinch the National League East. Their lead in the division remained 51 / 2 games with 12 remaining. The Cincinnati Reds also lost, which maintained the Nationals’ half-game lead in the race for best record in the NL.

As Clippard trudged from the dugout to the clubhouse, Jackson greeted him. Jackson told him to keep his head up, that he would be an important part of the Nationals’ success and it was vital for him to stay strong.

“He’s a gamer,” Jackson said. “So he’s all right.”

Jackson is right that the Nationals will need Clippard. For what role remains to be seen. He has proven he can close, but at the moment he is searching as Storen is dominating.

“We’re in a pennant race,” Clippard said. “Tonight would have been a big win for us. And that makes it hurt even worse.”