A large portion of the evidence presented in the salacious 35-page dossier put together by former British spy Christopher Steele, has either been proven wrong or remains unsubstantiated. However, the FBI gained approval nevertheless to surveil members of Trump’s campaign and "it’s outrageous and clearly should be thoroughly investigated," said a senior law enforcement source, with knowledge of the process.

Multiple sources told this reporter that the dossier was used along with other evidence to obtain the warrant from the Foreign Intelligence Surveillance Court, known as FISC. The sources also stressed that there will be more information in the coming week regarding systemic "FISA abuse."

"(The dossier) certainly played a role in obtaining the warrant," added another senior U.S. official, with knowledge of the dossier. "Congress needs to look at the FBI officials who were handling this case and see what, if anything, was verified in the dossier. I think an important question is whether the FBI payed anything to the source for the dossier."