Trumpian winner 

1. A candidate or competitor who wins on a technicality then occupies (or squanders) their tenure in a "braggadocious" attempt to prove that their triumph was a mandate by the people or by God
2. A person who has technically won a contest but is so insecure about themselves and the margin by which they won that they constantly bring up the competition, belittle their competitor, and inflate their own achievement long past the end of the contest
3. The equivalent of a sore loser, and yet they won
4. The loser of a contest who ends up winning on a technicality
5. Anyone who wins an election and models themselves after Donald Trump

That guy's a real Trumpian winner, still bragging about the election from a year ago.

Trumpian winner by Windup-Bird February 16, 2017