Once your proposal is almost done, it’s a good idea to prepare targeted messages to share it with in the group. Make sure to explain why what you are pitching is relevant for them. How will this proposal affect the organization directly and why should they care? Maybe even consider writing slightly different messages for specific sub-groups, so you can highlight parts of you proposal that have an impact on them. This can be a lot of work, but the more targeted the message, the better!