<img src="https://www.washingtonpost.com/wp-apps/imrs.php?src=https://arc-anglerfish-washpost-prod-washpost.s3.amazonaws.com/public/VIFUA5RWSYI63IGWIFJJTP7L2U.jpg&w=1024" /><br>At a White House event, the president is expected to offer his support for legislation that would require super PACs and so-called “dark money” groups to disclose donors.