Presidential candidate Donald Trump is under fire by the religious right organization National Organization for Marriage. The group tells voters to “Dump Trump” for “abandoning the fight for marriage,” according to Joe.My.God.

The group touted the ad in an email missive to supports and boasted that it “could cause some serious damage to the Trump campaign and thus help propel forward other pro-marriage candidates like Sen. Ted Cruz.” The group has endorsed Cruz in the Republican primary.

“This powerful new commercial could really make a difference in who wins in South Carolina. Most experts believe that the South Carolina race will come down to Donald Trump or Sen. Ted Cruz. When it comes to marriage, the two couldn’t be further apart. Donald Trump dumped the fight for marriage as soon as the US Supreme Court issued its illegitimate and anti-constitutional ruling, while Ted Cruz responded by sponsoring a constitutional amendment to restore the right of states to preserve true marriage,” the group wrote.

“As the ad makes clear, when Donald Trump quit on the fight for marriage, he quit on South Carolina and over 50 million voters across the nation who cast ballots defining marriage as one man and one woman.”

Cruz has actively courted the far right fringe of the evangelical Christian vote. Cruz was one of several Republican candidates who signed the group’s pledge to try to pass a constitutional amendment to ban same-sex marriage.

Watch the ad below.

https://youtu.be/6ablngXr7G8