Federal prosecutors have subpoenaed potential witnesses in what may be a broad investigation into Trump lawyer Rudy Giuliani's consulting businesses and other sources of income, the Wall Street Journal reported Monday.The subpoenas, which were issued to several people in Giuliani's inner circle, indicate that prosecutors are looking into possible money laundering, obstruction of justice, and campaign-finance violations. It is not yet clear if those charges are directly related to Giuliani's businesses and associates. However, one concern of the investigation is that Giuliani may have acted as an unregistered foreign agent or concealed lobbying work he did on behalf foreign nationals. Giuliani has denied lobbying for a foreign government.Giuliani told the Journal on Sunday that he has always referred his foreign clients to registered lobbyists when they've asked for help navigating the Trump administration.“All they have to do is come and ask me,” he said of federal inve...