U.S. Sen. Jeff Bingaman, chairman of the Senate Energy and Natural Resources Committee, took to the Senate floor to ask for an agreement to approve Hilary Tompkins, who served as counsel to Gov. Bill Richardson, as the U.S. Interior Department’s solicitor.

But, according to the New York Times, an anonymous Republican Senator has issued a procedural “hold” on the nomination of the Navajo lawyer.

This means that Tompkins is essentially blocked for the time being.

“I’m obviously disappointed there has been an objection raised,” Bingaman said according the New York Times. “It’s unclear why anyone would object to confirming Ms. Tompkins… More than four months into the new administration, the department should not be without its top legal (adviser). Ms. Tompkins should not be the victim of anonymous holds.”

A previous hold, by Sens. Bob Bennett, R-Utah, and Lisa Murkowski, R-Alaska, was lifted after they received answers from Interior Secretary Ken Salazar on the cancellation of oil and gas leases near national parks in Utah.

Both say each is not the anonymous Republican responsible for the current hold.

So what is a hold? According to the United States Senate official glossary:

An informal practice by which a Senator informs his or her floor leader that he or she does not wish a particular bill or other measure to reach the floor for consideration. The Majority Leader need not follow the Senator’s wishes, but is on notice that the opposing Senator may filibuster any motion to proceed to consider the measure.

Slate explains it in plain English, stemming from some controversial secret holds in 2006 on a government accountability bill.

What’s a secret hold?An anonymous objection that’s made before a bill hits the floor. The Byzantine rules of the Senate make it very easy for individual lawmakers to stall ongoing debates. Since anyone can slow down or halt the chamber’s business, the Senate must rely on collegiality to keep business moving forward. To that end, the Senate majority leader sets an agenda using “unanimous consent agreements” on what will be discussed and for how long.

Anonymous holds on Obama’s nominees have become almost commonplace.

The most notable case was the secret hold on Hilda Solis, Obama’s pick for Labor Secretary. The hold was eventually pulled and Solis was confirmed and sworn in as labor secretary.