The followiing quotation certainly applies to managing partners.
“What convinces is conviction. Believe in the argument you’re advancing. If you don’t you’re as good as dead. The other person will sense that something isn’t there, and no chain of reasoning, no matter how logical or elegant or brilliant, will win your case for you.” – Lyndon B. Johnson
It is often very difficult for a managing partner to “sell” a new idea to his/her partners. Some dig in their heels and block many new technologies, policies and procedures. You know who they are.
I urge you to never give up pushing for change and new ideas. You became managing partner because you are a great negoitiator. You have negotiated with clients for years (and also with partners). Use those negotiation skills with conviction to move your partners and your firm into the future.