Gate reviews are the forum for bid/no-bid decisions and for senior management sign-off on the strategy and progress you have made towards winning an opportunity. They determine whether the opportunity is still worth pursuing.
By contrast, the focus of colour team reviews is on improving the quality of the capture and proposal effort, with participants offering constructive recommendations.
It sometimes happens that senior management brought into a colour team review can disrupt the process by confusing it with a gate review. With this approach, they may forget to contribute constructively and question the premise on which the bid is proceeding.
When this happens, it indicates that the roles of the gate reviewers and colour teams have not been well defined and allocated. Ask your senior management sponsor to help you deal with the challenge by ensuring that the right people are “in the loop” and aligned with the capture effort in the appropriate roles.