Can you put a finer point on what you mean by "their interests"? Is this relegated to just economic interests?
If it extends beyond economics, I see no reason why those two statements can't coexist. For example, I can vote against my own economic interest if I vote for higher taxes that I don't directly benefit from on the grounds that I want to support a more equitable society. Or I can vote against government run healthcare that I may also benefit from if I don't think that is the role of government. Both can be examples of voting against my economic interests to reflect my moral interests.
Can you put a finer point on what you mean by "their interests"? Is this relegated to just economic interests?
If it extends beyond economics, I see no reason why those two statements can't coexist. For example, I can vote against my own economic interest if I vote for higher taxes that I don't directly benefit from on the grounds that I want to support a more equitable society. Or I can vote against government run healthcare that I may also benefit from if I don't think that is the role of government. Both can be examples of voting against my economic interests to reflect my moral interests.