Please.. you have to register to vote, you have to stand in a line for hours before you can vote. How many people don't vote because it's too much of a hassle? Their opinions are irrelevant?
Since some fraction of eligible non-voters wouldn't have voted no matter who the candidate was, the truth of the matter is obviously somewhere in between a quarter and a half. But there's no sense in which "half the vote" isn't misleading.
- People who voted in the last election
- People who have voted previously in an election
- People who are capable of voting (citizens of voting age not otherwise constrained from voting).
It's probably usually obvious which one is meant in a conversation, but there are also likely cases where it can be somewhat ambiguous.
Last time I checked, 46.09% of 55.3% was a little under 25.5% of all voters.