The impeachment of President Trump is effectively finished. The president will soon be acquitted. Calls from the right, and perhaps even the left, will follow: Move on.

Democrats would be smart to reject those calls, for both constitutional and political reasons. Despite an all but certain result in the Senate, Trump remains a threat to the fair administration of government and the country’s ability to hold a free election. And if history is any guide, his acquittal will only leave him emboldened to abuse his authority again. He is a recidivist. But impeachment has also shown that Democrats hold a strong check through their oversight powers in the House of Representatives. Between now and the time Trump leaves office, they will need to exercise those powers aggressively if they have any hope of curbing the president’s abuses. And they have demonstrated that they can curb them.

No matter the ultimate vote in the Senate, the House’s Ukraine investigation was successful. It exposed rampant wrongdoing to the American public, and it stopped cold that particular scheme of the president’s. We now know that before the chairman of the House Intelligence Committee, Adam B. Schiff (D-Calif.), began his investigation in September, the president’s plan was on track. After months of pressure, Ukrainian President Volodymyr Zelensky had scheduled an interview with CNN to announce an inquiry into the Ukrainian energy company Burisma, on whose board former vice president Joe Biden’s son Hunter once sat. Schiff’s announcement that a whistleblower had filed a complaint and his subsequent aggressive investigation killed that interview, and prevented the president from achieving his goal of casting a shadow over the Biden presidential campaign.

The Ukraine investigation accomplished what House Democrats had failed at previously. Passivity and ineffectiveness characterized the eight months of House Democratic control before the Ukraine scandal broke. The House let multiple administration officials who defied subpoenas off the hook by refusing to hold them in contempt of Congress, and it delayed for months going to court to enforce subpoenas of others. Before the Ukraine scandal, House committees held only a single memorable investigative hearing, the one featuring presidential adviser Corey Lewandowski. Lewandowski turned it into a farce.

Schiff’s investigation broke that pattern and established a road map for other committees. Even with impeachment finished, the administration will most likely continue to stonewall the House in its attempts to obtain documents and high-level witnesses, but Schiff proved that mid-level officials take their oath to the Constitution seriously and are more likely to worry about the consequences of defying a subpoena. Cases in point: former National Security Council aide Fiona Hill; former ambassadors Marie Yovanovitch and William B. Taylor Jr.; Ukraine expert Lt. Col. Alexander Vindman, and multiple other sitting officials from across the government. All testified under subpoena.

In continuing its investigations, the House can now ratchet up — or reclaim — its oversight powers by making clear that this threat is real. It can hold in contempt any witness who defies a subpoena and refer them to the Justice Department for possible criminal prosecution. Democratic presidential candidates could increase the House’s leverage over potential witnesses by stating that they will expect their attorney general to treat such referrals seriously and not allow witnesses to defy legitimate subpoenas. William P. Barr will not be attorney general forever. The House can also swiftly and aggressively litigate its subpoenas, asking courts to knock down the Trump administration’s unprecedented reliance on overly broad claims of privilege.

Democrats should also consider how Republicans have wielded their congressional oversight authority. During the Obama administration, Republicans used oversight as a torpedo designed to sink the Democratic nominee for the presidency. Their multiple Benghazi probes were not popular, but they were successful. It is not a stretch to say that Hillary Clinton would be president today were it not for aggressive House investigations. It was a Benghazi probe that unearthed her use of a private email server in the first place, and fear of Republican oversight that led the FBI to disclose its relaunched investigation into her emails in October 2016. Even now, Senate Republicans are launching their own investigation into Biden and his son.

But Democrats don’t need to be as shameless as Republicans to be successful. The Trump administration has served up a target-rich landscape to investigate; House Democrats need not fall prey to conspiracy theories or pursue politically motivated vendettas. Why was former national security adviser John Bolton concerned the president was granting personal favors to autocrats? Why has the president been handing out pardons and commutations to war criminals and conservative political allies while largely ignoring other applicants? What are the details of the president’s reported promises to pardon Department of Homeland Security officials if they would violate the law to build his election-year wall along the southern border? Even allies outside the administration are worthy targets: How about investigating reports that supporters of the president are handing out thousands of dollars in cash to voters.

Trump is a classic recidivist, and no amount of oversight will make him change his ways. As Schiff told senators in his closing argument in the impeachment trial on Monday: “He will not change and you know it.” But it is precisely because he is likely to continue abusing his powers that Democrats need to bombard his administration with subpoenas. Just as Schiff’s investigation stopped Trump from executing the Ukraine scheme, aggressive oversight can pressure people around the president not to carry out his lawless orders and encourage those with information to come forward and blow the whistle.

There will be a desire by some Democratic House members to abandon their focus on the president and return to legislating after the Senate trial — passing bills that go nowhere in a Senate ruled by Mitch McConnell and his Republican caucus, and have no impact on the public. But aggressively investigating the administration does not mean abandoning the legislative process. Proper oversight informs and strengthens Congress’s ability to legislate. After Congress uncovered the abuses of Watergate, for example, it passed multiple reforms to address corruption in government.

Throughout the impeachment debate, House Democrats argued that a failure to hold the president accountable would leave him free to abuse his authority to win reelection. They were right. But because Republicans in both chambers of Congress decided not to do their duty, Democrats will need to keep being aggressive in doing theirs. As they repeatedly proclaimed to the Senate, the price of inaction is too high.