Story highlights Roger Stone has known President Donald Trump for 40 years

Investigators asked questions about his contacts with an alleged Russian hacker

(CNN) The leaders of the House intelligence committee are warning that President Donald Trump associate Roger Stone will be slapped with a subpoena Friday if he does not reveal the name of his intermediary with WikiLeaks founder Julian Assange.

"We'll give it until tomorrow," Rep. Mike Conaway, the Texas Republican who is running the House panel's Russia investigation, told CNN Thursday.

Asked if the panel would subpoena Stone if he did not disclose the name by Friday, Conaway said: "Yes. We'll take the next steps. Hope we don't have to."

California Rep. Adam Schiff, the committee's top Democrat told CNN: "We have agreed to subpoena him if he doesn't provide the information. ... We'll see whether he's willing to comply or whether we'll have to use a compulsory process."

Grant Smith, a Stone attorney, said: "We are working to comply by the deadline set by the committee. Everything has been collegial and professional. There has been no threat of a subpoena."

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