So far, without much public scrutiny from Congress, the U.S. Department of Education has been able to issue 35 waivers that made big, big changes to the No Child Left Behind Act of 2001.

Many folks in Washington have been wondering whether lawmakers will take a closer look at how the waivers are playing out. After all, Secretary of Education Arne Duncan has said that the waivers could help inform a long-stalled renewal of the Elementary and Secondary Education Act, and that’s ultimately going to be Congress’ job.

Sen. Tom Harkin, D-Iowa, who oversees the Senate panels that deal with K-12 policy and spending, is likely to start looking into waiver implementation soon, although the details of exactly how that will happen are still being finalized, a Harkin aide said. “The Committee intends to examine how waivers are working in states to inform our work on ESEA. It will most likely come in the form of a hearing, but all of those details are still being worked out,” the aide said in response to my questions.

A hearing is likely to take place as early as next month, and will most likely include testimony from Duncan and state chiefs (who, after all, are the principal players when it comes to waiver implementation), other folks say.

There are a lot of questions for lawmakers to explore: How much flexibility did states get from the department? Were traditionally overlooked groups of students protected under the new systems? Do states like the waivers, or would they rather see an honest-to-goodness reauthorization? And what happens to the states that aren’t part of the waiver process?

The waivers, which required states to embrace certain education redesign priorities in exchange for flexibility from the mandates of the ESEA law, called for some big changes. For instance, a number of states are using “super subgroups” as opposed to looking separately at the progress of students in special education, English learners, and racial minorities. And states have been able to set new goals for bring students to proficiency on state standards. Plus, two states’ waiver bids have been rejected (California, which has a huge congressional delegation, and Iowa, Harkin’s home state.)

Lawmakers have already taken a few steps in the direction of oversight. Rep. George Miller, D-Calif, the top Democrat on the House education panel, sent a letter to the department back in September, which raised big questions about the way the waivers treat graduation rates. (In some states, for example, GEDs count.) Rep. John Kline, R-Minn., the chairman of the House Education and the Workforce Committee, has questioned the legality of conditional waivers. And Sen. Michael Bennet, D-Colo., the administration’s go-to guy on education policy, floated the possibility of oversight hearings on the waivers last year, in response to a reporter’s question at the Education Writer’s Association national conference.