I applaud your statistical sensibility, but I have a question – you're specifically looking for the margin of victory to be bellow the margin of error – but the margin of error of what, exactly?
Are you expecting the vote to be a proxy for the entire population of the country/state/whatever? Perhaps the entire population of eligible voters? Or, do you view it as simply the preference of those who took the time to vote?
Personally, I see little harm in disregarding the intentions of those who could vote but choose to not vote.
Issues of systemic inequalities in access to voting aside, I have little problem with viewing an election the task of accurately counting the votes of those who actually made it to the poling place. If you accept that concept, then the margin of error is extremely low – especially with electronic voting systems.