Sam,
The amount of assessments should be set to meet the amount (or expected amount) of expenses. The amount of money set aside to the Reserves is considered an expense in this case.
Since you are in CA, you should be aware that
CA law requires the Association to have a Reserve Study done. Additionally, per CA laws, a
Reserve Funding Plan must be adopted and published to the membership. Find out more about how CA sees Reserves by visiting davis-stirlings
Reserves menu web page. As a Board member, bring this information up.
Just because someone has a title, it does not mean that they have the authority.
The President is allowed to set the agenda, preside over the meetings and cosign checks. That's it. Unless your governing documents specify additional authority, that is all an Association President may typically do. However, many Boards relinquish their authority to others because they don't want to do the work.
The entire Board makes the decision by majority vote.
My suggestion is to remind the Board of their responsibility to do what is right for the Association as a whole and that doing this does not always mean doing what the membership desires. Then suggest that the Assessments should be established to fully fund the Reserves before any consideration is given to reduce the amount of assessments. Perhaps you can even provide handouts of the legal requirements for Reserves. Then, all you can do is vote against reducing the amount of assessments, make sure that your vote and the reason is included in the minutes and abide by the decision of the entire Board.