President Donald Trump accused Michigan Democratic Senate candidate Abdul El-Sayed of having ties to the Muslim Brotherhood during remarks at a White House Rose Garden lunch on Thursday, according to Fox News. Trump also called El-Sayed a “fraud” and “con man,” and said he planned to visit Michigan to criticize the candidate.

The accusations come amid Republican scrutiny of social media posts written in 2012 by El-Sayed’s half-sister, Eman Abdelhadi. In one post, Abdelhadi described speaking with their mother about her activism in the Muslim Brotherhood while she was in college in the early 1970s. In another, she wrote that her family had long been associated with the organization and criticized how it engaged in politics.

Those posts are Abdelhadi’s statements about their mother and family. The source does not provide independent evidence establishing the claims. El-Sayed has rejected allegations of family ties to the group. Asked about the issue in a recent NBC “Meet the Press” interview, he said, “I have no ties; we have no ties.”

El-Sayed also argued that his political opponents were emphasizing his name and Muslim faith instead of discussing his policy positions. He said Mike Rogers, his opponent, was urging voters to be suspicious of people because their faith differs from their own.

Trump, by contrast, asserted that El-Sayed was connected to the Muslim Brotherhood and questioned the prospect of him serving on the Senate Intelligence Committee. The source does not describe evidence Trump presented to substantiate that assertion.

Fox News reported that it had contacted El-Sayed’s campaign for comment. The supplied report does not include a response from the campaign. The allegations remain disputed: Trump made the accusation, Abdelhadi’s posts describe alleged family history, and El-Sayed has denied the connection.