I think based on the context of use in this situation that using "I may be extremely liberal" implies that you are indeed liberal and could possibly be very or extremely liberal. "I maybe extremely liberal" would actually be improper grammar and if used slightly differently would imply the fact that you may or may not be extremely liberal.
Please let me know if you need further clarification.
You are clearly stating that you are liberal. You are not stating that you are "extremely" liberal.
Another comparison would be "I may be in big trouble" which indicates you are in trouble and the word big is simply an adjective used to describe the level of trouble.
Does that provide sufficient clarification?