The midterm ad wars keep getting stranger.

Illinois Republican Gov. Bruce Rauner has an ad out this week depicting a mock wedding between Democratic rival J.B. Pritzker and state House Speaker Michael Madigan.

The 30-second TV ad, titled “Unholy Union,” features an officiator and stand-ins for Pritzker and Madigan at the altar.

The officiator begins, “Repeat after me: I, Mike Madigan, take you, J.B. Pritzker, as my unlawful partner in destruction -- to raise property taxes, corrupt government and bankrupt Illinois’ future.”

In the ad, the two characters swear to “honor and obey” each other. The officiant concludes, “By the power vested in me, I now pronounce Illinois f-----.”

Rauner is among the most endangered Republican governors in the country. Fox News’ Power Rankings rates the race as “lean Democrat.”

Pritzker’s campaign fired back at the ad, with a spokeswoman reportedly saying, “The people of Illinois are looking forward to their divorce from Bruce Rauner being finalized on November 6th.”

Pritzker told an ABC affiliate his opponent is “desperate.”

Meanwhile, the ad drew a backlash from gay rights groups.

"We are deeply disappointed by Gov. Rauner's new campaign ad that mocks marriage equality by tying two of his opponents together in a parody wedding," Brian C. Johnson, CEO of Equality Illinois, said in a statement. “The governor should be ashamed of using the LGBTQ community for comedic value to make a political hit.”

According to the ABC affiliate, Rauner has officiated gay marriages -- and defended the ad, saying: "That ad is about corruption and self-dealing and a broken political machine that Madigan runs and that Pritzker funds.”

Lauren Lee contributed to this report.