A billionaire investor and prominent Republican donor may be joining Marco Rubio’s inner circle.

Paul Singer, who endorsed Rubio in October, is slated to be named the candidate’s national finance chairman next week, sources told Politico.

Fortune reached out to Singer’s activist hedge fund, Elliott Management Corporation, and will update this post if the organization replies.

Since Singer’s endorsement of Rubio last year, his fund has emerged as one of Rubio’s top donors, according to records by the Center for Responsive Politics. Singer gave more money to Republican causes than any other donor in the country in 2014, according to The New York Times.

But Singer is also a prominent advocate for LGBT rights and gay marriage—an issue that could alienate evangelical voters from the Rubio campaign. In 2012, the billionaire launched a Super PAC to fund pro-gay rights Republicans.

According to the New York Post, a source close to Singer has denied Politico’s reporting.