The Democratic race for governor has been bitterly fought, and a recent poll showed the top two candidates — Christina Giunchigliani and Steve Sisolak, both Clark County commissioners — separated by only three points. Their contest has been vicious at times: Mr. Sisolak claimed in a recent ad that Ms. Giunchigliani had “single-handedly protected perverts” by weakening a sex offender bill years ago, to which Ms. Giunchigliani responded by revealing that she was sexually abused as a child.

Each hopes to be Nevada’s first Democratic governor since 1999.

Attorney General Adam Laxalt is widely expected to win the Republican nomination for governor. A son and grandson of former senators, Mr. Laxalt is a supporter of President Trump and has the backing of Sheldon Adelson and the Koch brothers.