At 10:18 on Tuesday night, when the only remaining mystery about control of the House of Representatives was the size of Democrats’ new majority, Representative Robert Garcia posted an all-caps message on X: “LAWYER UP.”Garcia, a Californian, was well placed to dispense that advice. Come January, he will chair the House Committee on Oversight and Government Reform—and, along with fellow-Democrats in the House and Senate, he will be newly armed with the power to hold hearings and issue subpoenas for documents and testimony from the Trump Administration and its allies.

In the past two years, congressional Republicans have exhibited a determined, see-no-evil indifference to President Donald Trump’s executive overreach and familial grifting. Democrats, meanwhile, have been relegated to holding unofficial hearings and seeing demands for information from Administration officials go ignored. As Garcia’s post suggests, that is about to change. Lawyers and lobbyists with expertise in congressional investigations and close ties to Democrats report being besieged by private-sector clients braced for a new world of oversight.

“Companies are not waiting for inquiries to begin, for very good reason,” Jamie Gorelick, who served as Deputy Attorney General under Bill Clinton and is now a senior counsel at the law firm WilmerHale, told me. “We are preparing multiple clients as we speak.”

Senator Sheldon Whitehouse, of Rhode Island, is set to become chairman of the Senate Judiciary Committee. Oversight, Whitehouse told me on Wednesday morning, “is an essential part of our Constitution’s checks and balances, and I think Republicans paid a heavy price for having utterly failed to meet their responsibilities in that domain.”Whitehouse said that, among other topics, he plans to address the Cava bag full of cash that F.B.I. agents posing as businessmen reportedly gave to Tom Homan, now Trump’s border czar, during the 2024 campaign. (Homan has said that he “did nothing criminal.”)

“What the hell happened to the fifty thousand dollars?”Whitehouse asked. “That’s a super easy one, and when we can’t even get that answer, I think that’s a pretty bad sign.”

Representative Jamie Raskin, of Maryland, is Whitehouse’s counterpart on the House Judiciary Committee. “There is no real legislative function without an oversight power, and here the oversight power is necessary in order to expose and then combat this curtain of corruption that has descended over the executive branch of government,” he told me on Wednesday.

Indeed, the list of matters ripe for oversight is daunting, including the politicization of intelligence, the awarding of no-bid contracts at the Department of Homeland Security, the operations of the pardon economy, and the extrajudicial killing of more than two hundred and forty supposed narco-traffickers.

None of this will be easy. Presidents from George Washington onward have wrestled with, and often bristled at, congressional demands. In Trump’s first Presidency, he took matters further, ignoring a blizzard of letters and subpoenas, directing officials and even private individuals not to comply with requests for information, and adopting an aggressive interpretation of executive privilege. Jonathan Shaub, a law professor at the University of Kentucky who served in the White House counsel’s office under Joe Biden, noted that the first Trump Administration “pushed a lot of these existing doctrines to their limit.”

Where other Administrations had sought to negotiate with Congress, Shaub added, “Trump said, basically, ‘No. This is all partisan warfare, and I’m going to pull out every weapon in my arsenal to fight you.’ ”That strategy of resistance was buttressed by a pair of Supreme Court decisions that augmented executive power. In the 2020 case Trump v. Mazars, the Court, citing the “weighty” separation-of-powers concerns, imposed a demanding test for congressional subpoenas of the President’s personal financial records; the oversight power, it said, is “justified solely as an adjunct to the legislative process.”

Then in the 2024 Presidential-immunity case Trump v. United States, the Court asserted that “Congress cannot act on, and courts cannot examine, the President’s actions on subjects within his ‘conclusive and preclusive’ constitutional authority.”Those rulings, Shaub said, “will be enormously powerful for Trump and his allies to use to at least stall the investigations.”Given the Administration’s ability to fend off Congress, lawmakers may want to focus on Trump Administration allies outside government.

Perhaps with that prospect in mind, the Justice Department’s Office of Legal Counsel issued an opinion in August contending that executive privilege could apply to Presidential conversations with advisers outside government as long as they relate to official Presidential matters, “involve or reflect communications with the President or his direct advisers,” and are confidential. This maximal reading of executive privilege may stretch too far even for this Supreme Court; still, it could offer Trump’s associates a way to delay compliance while the issue is litigated.

House and Senate investigators are apt to have more success, more quickly, obtaining compliance from companies, particularly publicly traded firms. Whitehouse observed, “For private entities to refuse to comply with a congressional subpoena is a much more hazardous step to take than if you are a political actor and are throwing all of this into a purely political partisan context. It’s not necessarily purely executive versus legislative here.”Raskin elaborated on that point. “We can subpoena pardon brokers. We can subpoena people who are ripping off the taxpayers in the private sector and working with people in the government,” he said.

“And we also have a ton of whistle-blowers who are coming forward on everything from the government contracting fraud that’s taking place to the $1.776 billion political slush fund to the Board of Peace. People seem to have had it with the reign of corruption and lawlessness. So we think that we will be able to get the information we need.”Democrats face risks in pursuing aggressive oversight, of course. Voters could be alienated by endless hearings if they do not see any accompanying legislative change.

Those on the left may press for a quick impeachment of Trump or of his top officials; moderate voters may be turned off by that approach. The Administration will do its damnedest to run out the clock, and on some counts may succeed. Yet Russ Anello, who served as deputy counsel to President Biden and previously as the staff director of the House Oversight Committee, believes that Congress will be able to examine many of the Administration’s apparent misdeeds.

“The first Trump Administration broke new ground with its stonewalling of Congress, but Congress still managed to get critical information,” Anello told me. “Even if the current Administration follows the same practice, Congress is still likely to get a flood of information from people in the federal government and the private sector who want Congress to conduct rigorous oversight.”The prospect for achieving some oversight, however imperfect, beats the current reality of none.