Marco Rubio on Tuesday accused GOP rival Ted Cruz of dirty tricks in South Carolina, just weeks after Cruz’s campaign was caught using questionable tactics against Ben Carson in Iowa.

Rubio’s presidential campaign cited a fake Facebook post attributed to one of his top supporters in South Carolina, Rep. Trey Gowdy, and charged that Cruz was behind it.

The post, from a now-defunct Facebook page called Trey Gowdy Prayers, says the congressman made a “grave mistake” by endorsing Rubio.

“It’s official, I have changed my mind. My previous endorsement of Marco Rubio was a grave mistake,” the fake post said. “The recent South Carolina debate revealed his total lack of integrity, intellect and foresight . . . To all my Christian and Conservative friends in South Carolina, I hereby formally endorse Ted Cruz.”

Gowdy called on Cruz to “repudiate these dishonest and underhanded tactics,” but Cruz denied that his campaign had any role in planting the fake post.

“Our campaign had absolutely nothing to do with this fraudulent Facebook post,” Cruz said.