"This is not a love-making process."

"This is not a love-making process." -- Prof. Charles Tiefer, testifying to Darrell Issa's committee on the subject: "Obstruction of Justice: Does the Justice Department Have to Respond to a Lawfully Issued and Valid Congressional Subpoena?"

Gary Martin of the Houston Chronicle's Washington Bureau reports "Lawmakers press feds for documents on cartel gun sales."

He also reports that the pressure is becoming bi-partisan.

House and Senate lawmakers are threatening to block presidential nominees and subpoena Justice Department officials this week to force the release of documents on a controversial gun trafficking program that allowed American shipments of weapons to Mexican cartels.

Congressional investigators claim U.S. officials allowed American gun stores to sell weapons in bulk to Mexican buyers in order to track the shipments and identify the ringleaders, known as "Operation Fast and Furious" under "Project Gunrunner."

Weapons from those sales were found at the scene of two separate attacks on U.S. agents, and Congress wants to know if they were used specifically in the deaths of Immigration and Customs Enforcement special agent Jaime Zapata or Customs and Border Patrol agent Brian Terry.

Sen. Charles Grassley, R-Iowa, claims the Justice Department and the Bureau of Alcohol, Tobacco, Firearms and Explosives is conducting a cover-up in its refusal to hand over documents and witnesses to congressional investigators.

Grassley, the ranking Republican on the Senate Judiciary Committee, said he will block President Barack Obama's nominees from confirmation until he gets the documents he needs for his panel's investigation.

In the House, Rep. Darrell Issa, R-Calif., will hold the first of several hearings today into the failure of the Justice Department and the ATF to cooperate with the congressional probes. Issa is threatening to issue subpoenas to retrieve documents and to gain access to witnesses.

Bipartisan support