Complex sentence: Waiz, a Democrat, was first elected mayor in 2003, defeating incumbent Tom Galligan in the May Democratic primary and then defeating Republican R. Monty Snelling in the November general election by nearly 20 percentage points.
Split into simpler sentences: Waiz, a Democrat, was first elected mayor after defeating incumbent Tom Galligan in the May 2003 Democratic primary. He later defeated Republican R. Monty Snelling in the general election by nearly 20 percentage points.