**SNIP** The dossier began as part of a conventional opposition research operation by a small Washington firm, Fusion GPS. During the early part of the campaign, Fusion was paid by The Washington Free Beacon, a conservative publication funded by the billionaire Paul Singer, to scrutinize Mr. Trump, with the evident goal of uncovering dirt to help his Republican primary opponents. After Mr. Trump emerged as the likely nominee, Fusion kept working but turned to a new source of funding: the law firm representing the Clinton campaign, Perkins Coie. Noticing in May 2016 the Trump campaign’s unexpected affinity for Russia, Fusion...