A constituency won with a small margin.
Something or somebody that is marginal.
Subject to a change in sitting member with only a small change in voting behaviour, this usually being inferred from the small winning margin of the previous election.
Written in the margin of a book.
Of, relating to, or located at or near a margin or edge; also figurative usages of location and margin (edge).
Sharing a border; geographically adjacent.
Of a value, or having a characteristic that is of a value, that is close to being unacceptable or leading to exclusion from a group or category.
Barely productive.
Pertaining to changes resulting from a unit increase in production or consumption of a good.
A voter etc. who has not yet come to a decision.
Uncommitted, not having reached a decision.
Open and not yet settled or determined.