Ready for a difficult mystery to solve?

Question

In a hotly contested city council race, there are three candidates. One night, two of the candidates meet in a bar. One downs a shot, asks for another, downs that one, and then waits a little, feling unsteady. The other slowly sips on his drink, talking amicably to the other. Later that night, he dies in his bed.

The police arrest the third candidate for murder and attempted murder.

Why?

Answer 1

cuz he was only left.

Answer 2

he was the bartender? waiter?...never got a tip?

Answer 3

he was talking in his sleep

Answer 4

He's the bartender!