The House Intelligence Committee has issued a subpoena to an associate of Sen. John McCain (R-Ariz.) over his connection with the controversial dossier containing unverified allegations about President Trump and his ties to Russia, The Hill confirmed on Wednesday.

Committee Chairman Devin Nunes (R-Calif.) wants to talk to David Kramer, a former State Department official and current senior director at the nonprofit McCain Institute, about his visit to London in November 2016, a source familiar with the matter confirmed. 

The Washington Examiner’s Byron York first reported on the subpoena.

While in London, Kramer met with the dossier’s author, former British spy Christopher Steele, at McCain’s request, to view “the pre-election memoranda on a confidential basis,” according to court filings.