Jeremy Hellickson lasted only three innings in the Nationals’ 6-5 loss to the Cubs. (Katherine Frey/The Washington Post)

The Washington Nationals needed one more hit — a homer, a timely single, something — to flip a terrible start into one of their best wins of a season short on good surprises.

That was the paper-thin margin between floating and failing Sunday night. That was the margin the Nationals had earned, one batter at a time, stirring up a late push after it seemed as if they may just roll over instead. But that hit never came, not this time, not in a 6-5 loss to the Chicago Cubs that dropped Washington eight games below .500 at 19-27.

Jeremy Hellickson buried the Nationals in one of his worst outings of an already disappointing year. The Cubs had four runs — scoring once in the first, second and third off Hellickson and in the fourth against reliever Kyle McGowin — before the Nationals collected their first hit in the fifth. Then came their comeback, spurred by Anthony Rendon and Howie Kendrick home runs, that fell a bit short.

“The boys played hard, all the way to the end,” said Manager Dave Martinez, and this time that was a cliche and the truth. “We’re down four runs, and they keep battling back.”

Not all of the blame could fall on Hellickson in his previous two starts, each lopsided losses for the Nationals and each strengthening the case to pluck him out of the rotation altogether. He was burned by bad first-inning defense in both outings. His ERA ballooned, but it still seemed possible that, with better support, he could again provide a solid five innings every fifth game.

Then Hellickson lost any benefit of the doubt.

“It hasn’t been bad, but today wasn’t good,” Hellickson said before letting out a deep sigh. He is now 2-3 with a 6.23 ERA through eight starts. The Nationals are 3-5 when he takes the mound. “I just got to get ahead and let my defense play a little more. Just walking way too many guys.”

He walked leadoff batter Kyle Schwarber on four pitches to begin his Sunday. He walked Kris Bryant on five. McGowin began warming up in Washington’s bullpen. Pitching coach Paul Menhart jogged out for a mound visit as the crowd at Nationals Park grumbled with frustration. Hellickson then walked Anthony Rizzo to load the bases with no outs and, on his 17th pitch, finally recorded an out while a run scored on a fielder’s choice.

Hellickson threw 22 pitches in the first, and seven of them were strikes. He gave up another run in the second after Jason Heyward singled, Albert Almora Jr. doubled and Schwarber knocked in Heyward with a sacrifice fly. He gave up another when Rizzo led off the third with a solo homer, his 11th of the year, his bat flicking an 89-mph fastball over the left field wall. And Hellickson’s night finished soon after, once he retired the Cubs and exited with this line: three innings pitched, three hits, three earned runs, three walks, one strikeout, 64 pitches thrown, only 30 of them strikes.

“I’m just a little off; I’ve never really fought my mechanics like this before,” Hellickson said. “I’m trying some new things, but I just got to throw more strikes.”

So it was McGowin, called up from the minors Friday, far down the 40-man roster when this season began, who had to clean up Hellickson’s mess in his season debut.

And as he did — or, rather, as he did his best to — Kyle Hendricks was close to losing his early rhythm. The Cubs’ soft-throwing starter needed 20 pitches to record six outs, 28 to record nine, and didn’t allow a base runner until he walked Rendon with two outs in the fourth. But he gave up one run in the fifth and, after yielding a walk and a single in the sixth, allowed the Nationals back in it on Rendon’s three-run homer that made it 6-4.

“Just getting people on base,” shortstop Trea Turner said of what changed against Hendricks. “With him, you try to get his pitch count up, you try to hit the strikes that he throws. He’s an interesting pitcher because he can throw an 80-pitch complete game if you don’t get on base.”

Juan Soto kept the sixth going with a double off the right field wall. Gerardo Parra extended it with a two-out single. That led Cubs Manager Joe Maddon to yank Hendricks and call Brandon Kintzler in from the bullpen. Kintzler, who used to pitch for Washington in big spots like this, stranded two runners in scoring position to end the innings. But he served up Kendrick’s leadoff homer in the seventh, and the Nationals were within a run with nine outs to go.

That placed the Nationals at a crossroads: Score two more runs to take back-to-back series for the first time this year, get Hellickson off the hook, push questions of their rotation depth to another day. Or don’t and again finish a night searching for just enough answers to piece together a convincing run.

The ending fit this season to date. The Nationals’ final breaths, before boarding a train bound for New York, were Kendrick grounding out to third, Victor Robles hitting a limp popup into Rizzo’s glove and Turner getting thrown out by a few steps at first. They didn’t accept defeat after they had every reason to. That counted for a very small something.

But they couldn’t win, and that always counts more.