On Nov. 7, Rep. Darrell Issa, chairman of the House Committee on Oversight and Government Reform, along with subcommittee chairman Rep. Jim Jordan, sent the White House a letter requesting testimony from top Obama aides Nancy-Ann DeParle and Jeanne Lambrew. Both are leading figures shaping the White House position in Obamacare design and implementation. Issa wanted them to appear at a Nov. 20 hearing on the so-far disastrous rollout of the president's national health care scheme.

"As the principal health policy advisor during the passage and early implementation of Obamacare, your testimony is vital for helping Congress understand the administration's preparation for and early implementation of Obamacare," Issa told DeParle.

On Tuesday, Issa got his answer: No. Neither DeParle nor Lambrew responded to the chairman's letter, but White House Counsel Kathryn Ruemmler told Issa he had no business asking the White House about the president's signature achievement.

Ruemmler began by listing some of Issa's information requests to the Department of Health and Human Services, the Centers for Medicare and Medicaid Services, the Internal Revenue Service, and others. Some officials from those agencies have testified or given interviews to Issa's committee, Ruemmler noted. And some have provided documents -- although Issa said at a hearing today that, "To date, HHS has not produced a single responsive document to this committee."

Nevertheless, Ruemmler told Issa that should be enough. "In light of the extraordinary information that has been provided to the Congress to date and the administration's ongoing efforts to respond to legitimate requests for information, I would encourage you to continue to direct your inquiries to the agencies responsible for implementing the Affordable Care Act," Ruemmler wrote. "Requesting the testimony of senior White House officials on the broad and amorphous range of issues referenced in your letter is an extraordinary step that is not tied to any legitimate oversight interest of the committee."

Telling a Capitol Hill chairman what is and is not in the interest of his committee is not the best way to smooth relations between the branches of government. But there is a long and contentious history of congressional investigators seeking testimony from the president's advisors. Sometimes they succeed; sometimes they don't. In this case, thought, a lot of Americans -- not just the Republican chairman of the House investigating committee -- would like to know what the White House knew about the state of Obamacare as its Oct. 1 debut approached, and what, if anything, White House officials did to prevent the approaching train wreck.

So Issa might ultimately get his answers. But for now, the White House won't talk.