President Trump in the Oval Office of the White House on Aug. 27. (Jabin Botsford/The Washington Post)

Adam B. Schiff, a Democrat from California, is the ranking minority member of the House Intelligence Committee.

Our democracy is broken, and President Trump is only one reason. Congress is the other. It has failed to serve as an equal branch of government, failed to play its essential role as a check and balance and, most glaringly, completely abdicated its oversight responsibilities.

It’s clear that we need a new majority that’s willing to hold this administration accountable.

In 1788, as the states considered ratification of the Constitution, James Madison acknowledged in Federalist 51 that those drawn to public service were not all angels, creating an inherent difficulty in establishing a government administered by imperfect beings: “You must first enable the government to control the governed; and in the next place oblige it to control itself.”

For nearly 2½ centuries, that is the way it has worked, with Congress serving as a restraint upon the executive and vice versa, and the courts serving to constrain both. It is certainly true that Congresses sharing the same party as the president have seldom been as diligent as those that do not. But devotion to country and the rule of law — if not the legislature’s own prerogative — has always been enough to stiffen the spine of Congress.

Until now.

The Republican Congress has not only failed to assert itself and review or investigate the conduct of the executive; worse, it has also been complicit in some of the president’s most egregious attacks on our democratic institutions.

The president’s recent push to selectively declassify portions of a Foreign Intelligence Surveillance Act warrant application regarding his former campaign adviser Carter Page and other materials in an ongoing investigation in which Trump himself might be implicated would never have been made if not for the encouragement of the chairman of the House Intelligence Committee. Instead of defending the intelligence community’s sources and methods and the independence of the Justice Department, Republicans in Congress are working in concert with the president to undermine both. And as the president acknowledged in a tweet, it took U.S. allies asking him to not act to pull him back from this ledge, at least temporarily.

But there is no better illustration of the wholesale surrender of Congress’s oversight responsibility than the moribund Oversight and Government Reform Committee. This committee, with the jurisdiction to investigate almost any activity across the entirety of the U.S. government, has failed to issue subpoenas for myriad disturbing allegations of malfeasance and incompetence in the Trump administration. No subpoenas during Environmental Protection Agency Administrator Scott Pruitt’s reign of corruption. No subpoenas as children were ripped from their parents at the southern border. No subpoenas over the president’s secret meetings with the postmaster general or administrator of the General Services Administration. No subpoenas as thousands died from neglect in Puerto Rico. Congressional Republicans, as former House speaker John A. Boehner so aptly put it, have been off “taking a nap.”

What will oversight look like under a Democratic majority? Given the wealth of disturbing conduct by the Trump administration, our caucus — led by Minority Leader Nancy Pelosi (D-Calif.) — will need to ruthlessly prioritize the most important matters first. In the Intelligence Committee, we will assess the work we have accomplished despite the Republican efforts at obstruction, along with what the Senate and special counsel Robert S. Mueller III have examined, and determine what else needs a full accounting. There are serious and credible allegations the Russians may possess financial leverage over the president, including perhaps the laundering of Russian money through his businesses. It would be negligent to our national security not to find out.

In the Oversight Committee, ranking Democrat Elijah E. Cummings (Md.) has said he wants to scrutinize bread-and-butter issues, such as the high cost of prescription drug prices, and corruption issues, including whether Trump is profiting off the presidency. On the Judiciary Committee, ranking Democrat Jerrold Nadler (N.Y.) is demanding oversight of potential abuse of the pardon power, attacks on the rule of law, and campaign finance violations. And Democrats on the Veterans’ Affairs Committee want to make sure veterans are getting the best care and that decisions are being made by the professionals, not Trump’s unelected cronies.

For a role so vital to the proper functioning of our government, Congress’s oversight function is not explicitly mentioned in the Constitution. This was not due to any failure of the framers to appreciate the importance of Congress using all means at its disposal to ensure that the executive honors his or her responsibility to “take Care that the Laws be faithfully executed.” Quite the contrary: The rigorous exercise of oversight was an unquestioned presumption if, as Madison wrote, ambition was to counteract ambition.

Make no mistake, our first task will be to put forward a positive agenda for the American people — one that focuses on raising incomes and lowering health-care costs. But at the same time, we must do what the supine Republican Congress has failed to do over the past two years: restore Congress as an equal branch and check the ambition of an imperial and erratic president.