Referendum and sequencing/impulse

Casting votes should stay as it is. You shouldn't be forced to declare how you vote (or abstain) just because it's your turn around the table - you decide to cast votes (or not) in reaction to the current vote balance and ongoing table negotiations. This is politics.

It might be a bit messy but only if more players are sure how they want to vote and that they want to vote immediately - but that's just "human" issue, game mechanics are unaffected, you can vote all at once.