After a tense exchange with Acting IRS Commissioner Danny Werfel Friday, House Oversight and Government Reform Committee Chairman Darrell Issa sent a subpoena to the Treasury Department Friday demanding more documents and accusing the agency’s chief counsel’s office of being “compromised.”

Issa, R-Calif., accused the Internal Revenue Service of dragging its feet in responding to the committee’s demand for documents related to IRS targeting of conservative groups — a charge Werfel denied.