Sign-off on the proposal does not occur the day it is presented to management. If you hope to gain sign-off, concurrence from the management team must occur well before the proposal is submitted for their final review. This concurrence can be easy if you establish management buy-in early on in the proposal development phase. It is important to keep the management team close to your progress through direct involvement in the way of a very strong communication and feedback loop.
Frequent proposal status and review meetings will ensure that you have management's buy-in as you progress through development. Be sure to solicit and incorporate each member's direct input even if you have to do it through one-on-one reviews. People are not inclined to reject a document that contains their own ideas; therefore, finding a way to get them involved is imperative.
Although it sounds pretty easy, gaining buy-in is not always straightforward. Not everyone on the management team may share your objectives or your convictions; you need to assess and classify each member of the management team as either a supporter, a non-supporter, or "on the fence."
Just because someone is a supporter does not mean you will get his or her support and sign-off by default. It does mean, however, that you should not have to expend much energy selling them conceptually. You do, however, still have to spend time soliciting their input and selling them on your approach.
A non-supporter will obviously be your most difficult challenge, because you must sell them both conceptually as well as on the overall approach. I wish there was some magic formula, but it is just not that simple ”you will need to roll up your sleeves and work to gain their support. Experience shows that to gain this support, it is essential that you keep all outputs and discussions fact-based , and keep emotion out of the equation. If you keep the facts vague, and rely on "cheerleading" and emotion, you run the risk of the non-supporter perceiving you as promoting an agenda. In addition, here is where seeking input and "overcommunicating" plays a big role. No matter what the outcome, do not become discouraged because you may not be able to ever sway the non-supporter your way, so best you can hope for is majority support.
People "on the fence" will generally behave in one of two ways. They will either be swayed by the majority opinion, or they will be swayed by a particular individual whom they deem as a subject matter expert or whose opinion they hold in high respect. Winning them over will rely on your ability to assess what type they are. In any case, this does not relieve you of the need to remain fact-based and to solicit input.
If you are able to successfully build coalitions and gain buy-in early, management sign-off should truly be nothing more than a formality . If you have any doubts about whether or not the proposal will be approved, then you probably have not kept the management team close enough.