Casey DeSantis, the wife of Gov. Ron DeSantis of Florida, drew criticism on Saturday from the rival campaign of former President Donald J. Trump for seeking to recruit out-of-state supporters to participate in the nation’s first Republican nominating contest.

The backlash came a day after Ms. DeSantis, during a Fox News appearance with her husband, urged supporters from elsewhere to “descend upon the state of Iowa to be a part of the caucus.”

“You do not have to be a resident of Iowa to be able to participate in the caucus,” said Ms. DeSantis, who has been a key player in her husband’s campaign and was specifically addressing mothers and grandmothers who support him.

But the call to action is at odds with caucus rules, according to the Republican Party of Iowa, which hours later said that nonresidents were barred from caucusing.

“Remember: you must be a legal resident of Iowa and the precinct you live in and bring photo ID with you to participate in the #iacaucus!” the party wrote on the social media platform X.

Mr. Trump’s campaign on Saturday accused the DeSantis campaign of spreading misinformation about the caucuses, which will be held on Jan. 15. It suggested that the move was part of a broader scheme to change the outcome in the state, where polls show that Mr. Trump, the Republican front-runner, has a significant lead.

“The Trump campaign strongly condemns their dirty and illegal tactics and implores all Trump supporters to be aware of the DeSantises’ openly stated plot to rig the caucus through fraud,” the campaign said in a statement.

In an email on Saturday, Andrew Romeo, a spokesman for the DeSantis campaign, drew attention to comments made later on Friday by Ms. DeSantis on X, attempting to clarify her earlier remarks.

“While voting in the Iowa caucus is limited to registered voters in Iowa, there is a way for others to participate,” Ms. DeSantis wrote.

Mr. DeSantis also addressed the controversy while speaking to reporters on Friday in Iowa.

“While voting in the Iowa caucus is limited to registered voters in Iowa, there is a way for others to participate,” he said. “They even let people go and speak on behalf of candidates, and they have all these precincts, so you may have people who really can speak strongly about our leadership that are going to come.”

The Trump campaign continued to seize upon Ms. DeSantis’s remarks on Saturday, calling on Gov. Kim Reynolds of Iowa, who has endorsed Mr. DeSantis and snubbed Mr. Trump, to clarify the caucus eligibility rules. It also demanded that Ms. Reynolds disavow the tactics promoted by Ms. DeSantis as “flagrantly wrong that could further disenfranchise caucusgoers.”

A spokesman for Ms. Reynolds did not immediately respond to a request for comment on Saturday.

Kellen Browning contributed reporting from Iowa.