Republican presidential nominee Donald Trump, who has struggled to drive a consistent message and consolidate the support of his own party, is honing his attack on Democratic rival Hillary Clinton and the foundation bearing her last name, making it a rallying cry for fellow Republicans to get behind his campaign.

Trump began this week hammering her for the Clinton Foundation, an organization created by her and her husband, former President Bill Clinton, which uses private donations to fund aid programs in developing countries.

On Monday, he called for the foundation to be shut down. On Tuesday, he called for a special prosecutor to be named to investigate the foundation.