WASHINGTON — The rookie pitcher debuting in the major leagues gave the Mets a chance Wednesday.

So too did the lineup that took hacks against the Nationals, but it hardly succeeded. This was a reversion to before the last homestand, when the Mets routinely underperformed offensively, regardless of the opposing pitcher.

On an overall uninspiring night, the Mets sputtered to a second straight loss, 8-4 at Nationals Park.

Juan Soto kept the Mets in the game by blasting two homers, including a two-run shot in the eighth that brought hope of a comeback victory that never materialized. Soto has five homers in his past seven games.

Zach Thornton, selected from Triple-A Syracuse to replace Clay Holmes (fractured right fibula) in the rotation, had a rough first inning, allowing a three-run homer, before getting on a roll following another run surrendered in the second. The left-hander retired nine of the final 10 batters he faced.

“I feel as though I belong here and my stuff is going to play,” Thornton said. “So, if I can just get in the zone, I will be all right.”

How nervous was the 24-year-old before the start?

“I am nervous before every game I pitch,” he said. “This was kind of nothing new.”

Thornton kept the Mets competitive by allowing four earned runs on four hits and two walks with three strikeouts over 4 ¹/₃ innings. He was removed at 80 pitches before he could face the Nationals a third time through the batting order.

“They ran his pitch count up, and the one thing that I liked, even after he got punched there in the first inning, he didn’t back down,” manager Carlos Mendoza said. “He kept going after them and his pitch count went up, but he competed though.”

It’s possible Thornton won’t stay long: The Mets may promote Jonah Tong to start this weekend in Miami, giving extra rest to the rotation, and Thornton could lose his roster spot in the transaction.

Thornton was welcomed to the major leagues by CJ Abrams’ three-run homer in the first inning. Curtis Mead singled and Andrés Chaparro walked before Abrams unloaded to right-center.

The Mets pulled to within 3-1 in the second on Brett Baty’s RBI single after Mark Vientos doubled leading off against Zack Littell. A.J. Ewing provided an additional single in the inning before Littell struck out Hayden Senger.

Nasim Nuñez walked in the second and stole second, reaching third when Senger’s throw sailed into the outfield. Keibert Ruiz’s ensuing RBI single extended the Nationals lead to 4-1. But Thornton was finished allowing runs for the night.

“It was just getting back to what I do best, which is getting two strikes before I get to one ball,” he said.

But the Mets reclaimed the run in the third on Soto’s massive blast off the mezzanine in right.

Carson Benge’s arm helped save the Mets a run in the fifth. Luis García Jr. stroked a two-out single to right field, on which Benge threw a strike to Senger, who tagged Ruiz sliding into the plate for the final out. Ruiz doubled for the final Nationals base runner against Thornton.

Austin Warren surrendered a run in the sixth that extended the Nationals lead to 5-2. Abrams and Dylan Crews both singled before Daylen Lile hit a sacrifice fly.

Nuñez’s sacrifice bunt brought in the sixth Nationals run after Jacob Young’s double. Craig Kimbrel got the final two outs in the sixth.

Young hit a two-run homer against Kimbrel in the eighth that completed the Nationals’ scoring after Soto had homered in the eighth.

Soto was asked to describe even the slight difference when he’s so locked in at the plate.

“I can do damage,” Soto said. “I can do a lot of damage that I can help the team be where it needs to be.”