"Design consensus" is an unwelcome term in design circles because it reeks of "design by committee." In a corporate environment, though, consensus can be a designer's best friend— if you know when to seek it out.
Don't always seek a consensus
In reality, seeking a consensus isn't always a good idea. Individual thoughts and ideas can be great for maintaining consistency while collaboration can sometimes take forever. If you're considering getting consensus on something, ask yourself if it's needed in the first place— maybe the project can thrive without the input of a dozen other people.
If the risk of individual decision-making isn't too costly, or the risk doesn't need to be mitigated with informed business decisions, then forget about seeking a consensus all together.
When to build a consensus
If consensus is called for, figure out the goals of everyone on the playing field. Are there advocates that understand good design? Can you align everyone else's thinking with your vision? If not, maybe you need to punt until you have a clearer picture of the team's goals.
Whatever you do, don't open up the whole problem to collaboration or you'll have chaos on your hands. Instead, break the problem into smaller parts and dole them out for specific advice from people in different business units. You're looking for buy-in at this point so put your best foot forward and sell what you know.
Finding consensus can become a complex situation very quickly, so a designer needs to take the reins and keep the process from stagnating. Let the team know that non-response is considered an acceptance of the idea, and you'll take it as a green light to move forward. Once you get the organization used to processing feedback and ideas this way, you'll get more control over the conversation and discover design consensus isn't really that terrible of a process after all.