Brown is seeking reelection against Republican businessman Bernie Moreno in the nation's costliest U.S. Senate race. Republicans and Democrats spent nearly $477 million on the race, according to AdImpact,

Ohio's $467 million U.S. Senate race is now the most expensive non-presidential contest on record, according to AdImpact.

Incumbent U.S. Democrat Sherrod Brown has been serving Ohioans since 2007.This year, he's being challenged by Republican Bernie Moreno, a businessman and owner