[Chandraa]

First, get a sense for why the middle managers are against the system. Are they afraid of losing their jobs? Do they believe that it will add more friction to their process? You can do this by getting the stakeholders on a call and asking them to explain the why (which will make them feel included and important). Or if you can, visit them and say you want to shadow them to understand the process and in doing so get into their minds.

Once you get that clarity, work with them to design a solution that works for them, and make it look like it's their idea not yours. Make them look brilliant.

Much of success in hostile environments boils down to identifying the motivations of people and making new ideas theirs not yours.