Things are becoming increasingly ugly as the Alabama Republican primary runoff approaches. Behind in the polls and with his back against the wall, incumbent Sen. Luther Strange attacked challenger Roy Moore for failing to protect children from sexual abuse while chief justice of the state Supreme Court.

The Strange campaign cut an ad accusing Moore of letting an African American man off easy after he abused four young children at a daycare. Chilling and dramatic, the 30-second spot is reminiscent of the Willie Horton attack ads played against Democrat Mike Dukakis during the 1988 presidential campaign.

Unrattled and only a few hours before Trump was set to hold a rally for Strange, the Moore campaign slammed the ad as "an exaggeration and a distortion" before dismissing it completely as "a sign of losing desperation."

Until now neither candidate had made crime an issue. With four days before the runoff and ahead of Trump's visit though, Strange has tried forcing the issue, pointing to the 2015 case when the candidates crossed paths as attorney general and Supreme Court justice. Strange argues that Moore wanted to go easy on Eric Lemont Higdon, a 17-year old boy who abused four children under the age of five.

The Moore campaign defends the judge's lone dissent in the case, arguing that he made it because of constitutional considerations, not criminal leniency.

"Judge Moore has an ironclad record of allegiance to the constitution and a commitment to justice for victims," Moore spokesman, Brett Doster, told the Washington Examiner, adding that the opinion of his boss "was related to legislative definitions separate from the defendant's maximum sentence of 23 years in the state penitentiary."

Voters might look past that record though and take Strange's attacks at face value if Trump makes crime an issue at tonight's rally. The president has repeatedly endorsed "Big Luther" as the law and order candidate.

Philip Wegmann is a commentary writer for the Washington Examiner.