Rep. Darrell Issa (R-Calif) can't stop issuing subpoenas. Since becoming chairman of the House Oversight and Government Reform Committee in 2011, Issa has issued nearly 100 subpoenas – more than the last three committee chairman combined, according to Rep. Elijah Cummings (D-Md). (Cummings is the ranking member on the oversight committee, but he and Issa really don't like each other.) Cummings points out that Issa's 96 subpoenas have been issued without any debate or vote in the committee. In a letter to Issa, Cummings argues that “issuing unilateral subpoenas with no legitimate justification undermines the credibility of this committee.”

Many of Issa’s efforts appear to pure mischief making — not all of which are appreciated by his own party. Take his persistence with John Kerry. He subpoenaed the secretary of state on May 2, ordering Kerry to appear before the Oversight Committee after the House voted to establish the Benghazi select committee. This subpoena was then was rescinded and followed by another subpoena on May 15 after Issa realized Kerry would be out of the country on the initial hearing date. This second one was withdrawn after House Republicans described Issa's maneuvers as a “procedural snafu.” Kerry has yet to appear.

Then there’s Issa's efforts to subpoena the IRS commissioner, attorney general, the Bank of America, the Department of Health over Obamacare, the U.S. Treasury Department, the Justice Department, the National Park Service, Health Secretary Kathleen Sebulius and 28 years of FEC records. The list goes on and on.

But his most recent subpoena, issued to a senior Obama adviser, has caused much bafflement. Issa has ordered David Simas, the director of the White House Office of Political Strategy, to testify over potential violations of the Hatch Act on July 16. The political strategy office was reopened earlier this year (after Obama closed it in 2011) in a move Issa believes “heightens concerns about the illegal use of taxpayer funds to support congressional campaigns during the 2014 midterm elections.” A congressman demanding testimony from someone in the White House raises issues hackles about separation of powers. Therefore, the White House Counsel has asked Issa to withdraw his request, offering a private meeting to discuss the political strategy office instead.

Even if Issa doesn't withdraw the request, will David Simas come? Paul Light, author of Government by Investigation: Congress, President, and the Search for Answers, 1945–2012, believes Issa has been “overusing the cudgel, and thereby weakening the great investigative threat." Light reckons "at some point, overuse turns the subpoena into a running joke.” Could the Simas subpoena be that moment? Light thinks there is “no chance” that Issa’s subpoena will bring Simas to the Hill tomorrow.

Issa has refused to back down. His spokesman said this morning "the subpoena for Mr. Simas’ testimony remains in effect. The White House has had multiple opportunities to work with Congress to date, and has neglected to do so. Chairman Issa has allowed that if the White House provided the requested information to the Committee, he would reconsider but at present Mr. Simas is still expected to appear at Wednesday’s hearing."

Tomorrow looks set to add another twist in the ongoing battles between Congress and the White House.