Trump

A person who is a sore loser.

Someone who lacks credibility and invents baseless and unsubstantiated claims of cheating and fraud when they lose.

"You're such a Trump, you lost, accept it!"

"Mate. You lost! Don't be a Trump and embarrass yourself. Be a man!"

"The only reason I lost is because they cheated and there's fraud" - "No! You lost because more people voted for the other guy! You're such a Trump!"