“They need to issue a subpoena with a drop dead date and a promise of jail time for failing to meet that date.”
The problem is who is going to enforce it? Holder? Who is available to put the person in jail?
From Wikipedia:
Procedures
Following the refusal of a witness to produce documents or to testify, the Committee is entitled to report a resolution of contempt to its parent chamber. A Committee may also cite a person for contempt but not immediately report the resolution to the floor. In the case of subcommittees, they report the resolution of contempt to the full Committee, which then has the option of rejecting it, accepting it but not reporting it to the floor, or accepting it and reporting it to the floor of the chamber for action. On the floor of the House or the Senate, the reported resolution is considered privileged and, if the resolution of contempt is passed, the chamber has several options to enforce its mandate.
Inherent contempt
Under this process, the procedure for holding a person in contempt involves only the chamber concerned. Following a contempt citation, the person cited is arrested by the Sergeant-at-Arms for the House or Senate, brought to the floor of the chamber, held to answer charges by the presiding officer, and then subjected to punishment as the chamber may dictate (usually imprisonment for punishment reasons, imprisonment for coercive effect, or release from the contempt citation).