WASHINGTON — The Mets’ pitching plan right now entails rolling with the same five starting pitchers and not adding a sixth.

That would involve having Kodai Senga pitch on Monday against the Phillies with only four days of rest—a first since 2023—followed by Sean Manaea and Nolan McLean also pitching on four days’ rest. The series against the Marlins next Thursday would then open with Clay Holmes, also working on regular yet irregular four days’ rest for Mets starting pitchers.

This season, Mets starters have been tasked with pitching on four days’ rest just 22 times, largely because Senga is used to a five-day routine, and Holmes benefits from an extra day as he adapts from bullpen duties. In those specific games, the Mets’ starters have posted a 5.55 ERA.

On Wednesday at Nationals Park, the Mets suffered a 5-4 loss, marking the second game in their challenging sequence of 16 games across 16 days. They are not planning to incorporate a sixth starter, which would have provided additional rest for the rotation.

“The advantage early in the season is, you can spread the workload out a little bit,” pitching coach Jeremy Hefner said. “And then when you have these situations where you have a lot of games in a row at the end of the season, it makes some sense if they’re feeling good and responding well, then you do it.”

The Mets feel that the entire group is responding well, before Senga gave up five runs (four earned) on six hits in five innings Wednesday. If they stick to the plan, it would mean Senga pitches on shorter rest for the first time all year.

David Peterson, who will pitch Sunday on four days’ rest, carries a 7.20 ERA in four games in such scenarios.

Holmes owns a 4.12 ERA on four days’ rest and a 3.34 ERA on five days’ rest.

The alternative would be to add Frankie Montas back into the rotation or call up Brandon Sproat, who pitched Tuesday for Triple-A Syracuse for the first time all season on four days’ rest.

But Hefner said the change in schedule for the top prospect was happenstance, resulting from the Syracuse team losing McLean.

Bringing up a pitcher such as Sproat — who has been excellent since the end of June — would be complicated for a team that does not have much roster flexibility.

Such a move might force Reed Garrett, the only optionable reliever, back to Syracuse, and Garrett has been an integral part of the team.

Or an addition could prompt the DFA of Ryne Stanek, who has struggled but carries 100 mph heat and a strong postseason résumé.

The Mets will add some flexibility Sept. 1, when perhaps Sproat or the rehabbing Tylor Megill can be brought up with an additional roster spot.

But there are no plans at the moment to add another starting pitcher, which of course could change if performance or poor recovery dictates it.

Megill is expected to make a third rehab start Sunday.

The righty, recovering from a right elbow sprain, most recently threw 3 ¹/₃ innings and 55 pitches with Double-A Binghamton on Sunday.

There is optimism that Jose Siri will play again this season. There is less optimism that Jesse Winker will be back.

Siri, who fractured his left tibia after just 10 games, is expected to begin a rehab assignment next week, manager Carlos Mendoza said.

Winker, who has played two games since early May and is on the 60-day injured list with back inflammation, is “having a hard time recovering at times,” Mendoza said.

Winker has not been able to progress and has done limited activities.

“As of right now, the goal is for him to be a player for us at some point,” Mendoza said. “But again, we just got to wait and see.”

Mark Vientos started for a third straight game after homering in his past two contests. Ronny Mauricio had not played since Saturday.

“There’s competition, and [Vientos] continues to earn playing time,” Mendoza said. “We need him. He’s a really good player.”