The hardest sell for the Mets baseball operations department leading up to the trade deadline is not persuading suitors to make substantial offers for Edwin Diaz and Noah Syndergaard. It will be convincing ownership to accept such a deal if it reaches a level perceived acceptable.

Teams pursuing particularly Syndergaard describe the Mets as, in the words of one executive, “listening more” to what could be acquired. But the dynamic portrayed also is that Brodie Van Wagenen and his staff do not want to present anything to ownership until it is overwhelming enough that the Wilpons might say yes.

One person familiar with the Mets operation said the Wilpons are aware of their reputation for micromanaging and have told baseball operations not to come to them until talks grow serious. As of late afternoon Thursday, one source told The Post, nothing to that level had yet materialized.

But the Padres and their deep farm system are definitely interested — as they were in the offseason — and so are the Astros and others. Allard Baird, the Met vice president for scouting and development, and special assistant to the GM Omar Minaya — probably Van Wagenen’s two most trusted set of eyes — on Thursday were watching the Braves’ Triple-A and Double-A affiliates, respectively. Atlanta was the most interested team last year in Zack Wheeler. But the Braves also have the farm depth to get Diaz or Syndergaard, if the Mets were willing to trade them within the division.

They almost certainly don’t have the stomach to trade them in the same city, though the Yankees and Mets did discuss Syndergaard in the winter.

Swaying the Wilpons to agree to trade Diaz and especially Syndergaard will be arduous.

The concept of trading one or both would not be to rebuild, but to try to create a better overall team moving forward by deepening the talent pool and gaining future financial flexibility. But an executive with extensive dealings with Mets ownership wonders if Fred Wilpon, in particular, appreciates the more modern roster-building sensibility that favors youth, depth, versatility and financial flexibility.

For example, this executive said if the Mets were offered the equivalent of Tyler Glasnow, Austin Meadows and Shane Baz for Syndergaard that ownership might not appreciate the quality. That was the trio of players the Rays received in a winning trade last July for Chris Archer.

Also, there are concerns about being embarrassed talented players such as Diaz and Syndergaard, who have underperformed this year for the Mets, will be unlocked and flourish elsewhere. There is a particular worry about sending either to a more analytically advanced organization such as the Astros — and you could just imagine the pain if either were thriving for the Braves or Yankees.

Ownership also has trust issues after Van Wagenen’s first offseason went so poorly. The Diaz deal most problematically cost the Mets two of their best prospects, notably outfielder Jarred Kelenic, who is now viewed among the best prospects in the game. Plus, the Mets took on the final five years of Robinson Cano’s contract through age 40.

So when it comes to Diaz, one interested executive said, “They are open, but I think they are trying to exceed what they paid.” With Diaz struggling that will be a difficult — perhaps impossible — request to meet. As for Syndergaard, an AL official said, “It’s tough to trade [Syndergaard] and make the kind of multiple acquisitions that will leave [the Mets] feeling they have moved the needle forward to a better, contending team next year. That is hard. That is why I am skeptical he will actually move.”

If ownership lacks trust in the front office it can always try to regain faith by seeing smaller moves executed and delay bigger decisions until later. Syndergaard is not a free agent until after the 2021 season and Diaz is under control until after 2022. So there is no deadline that must be met. And one Mets official noted that the organizational belief is that it is tough to acquire or develop high-impact players and that they view Diaz and Syndergaard as that and in their 20-something primes.

However, there is a marketplace craving high-end pitching and despite their subpar results Diaz and Syndergaard are high-end talents. Syndergaard’s power stuff is specifically desired in the playoffs by contenders.

So the Mets baseball operations department is more seriously engaged to see if it can reach a price that not only satisfies it — but, more important, ownership too.