On January 3, 2019, a new Congress will head to work with a monumentalbut not unprecedentedjob to tackle. Close observers of Special Counsel Robert Mueller’s investigation predict his “endgame may be in sight.” While Mueller’s work may be drawing toward a close, Congress’s has just begun. As my organization, Protect Democracy, set forth in a collection of reports published this week, Justice Department investigations of executive-branch wrongdoingespecially those that implicate the presidentserve as source material, not substitutes, for congressional oversight and legislative reform. If President Donald Trump or his campaign worked with Russian agents to swing an election in his favor, or impeded the Special Counsel’s investigation of a Russian counter-intelligence operation, the American people need to understand how and why that happened and participate in informed debate on policy solutions that will prevent it from happening again. And regardless of what Mueller establishes with respect to criminal liability, Congressand the American peoplemust assess the appropriate measure of political accountability if the president committed wrongdoing to win the election or abused the powers of his office.

Of course, Trump has made a career of escaping accountability, and he’s trying to do so again. He repeatedly moves the goalposts in his denials of responsibility for the Kremlin’s electoral machinations. First, he had “nothing to do with Russia.” Then maybe he had something to do with Russia, but there was “NO Collusion!” We now hear that “collusion is not crime,” or maybe if it’s a crime, it shouldn’t be because of the First Amendment. Congress should not let him get away with these attempts at evasion.

The Framers of our Constitution took great pains to preclude foreign influence over our leaders and preserve self-rule for the American people. There can be no doubt that working with a foreign power to influence a federal election is a seriousand criminaltransgression of the principles that inspired our nation’s founding. If Trump, his campaign, or his associates coordinated with Russia to further its criminal interference with the 2016 election, it would constitute a “conspiracy” to commit not just a crime, but potentially many crimes. As we explain in our report When Mueller Concludes: If Conspiracyby Whatever NameOccurred, Congress Must Ensure Accountability, the federal criminal conspiracy statute (18. U.S.C. § 371), the Federal Election Campaign Act, the Computer Fraud and Abuse Act, the Logan Act, federal bribery laws and the Hobbs Act, and misprision of a felony all could be implicated.

And the Trump campaign’s the-First-Amendment-lets-me-do-it defense to these potential crimes is both remarkably cynical and legally wrong. As Judge Brett Kavanaugh wrote in a 2011 opinion, the Supreme Court has made plain — indeed, beyond rational debate its view that the federal government may outlaw support from foreign citizenslet alone agents of a hostile foreign powerto win elections. The First Amendment protects speech and even some expressive acts, but courts have long upheld statutes establishing criminal penalties for soliciting others or conspiring to engage in criminal activity. While a political candidate is free to articulate his or her vision for the country, he or she is not free to solicit any campaign help from a foreign government. The former is “speech”; the latter is a violation of federal campaign finance law and a range of other criminal statutes.

The president’s lawyers — and, apparently, his nominee for Attorney General have offered an equally cynical and unconvincing defense of allegations the president has abused his powers to interfere with Mueller’s investigation. A president, they say, can’t obstruct justice because, “by virtue of his position as the chief law enforcement officer … that would amount to him obstructing himself.”  Or, as Richard Nixon put it, “when the president does it, that means that it is not illegal.”   

But the president is not above the law. Our report, When Mueller Concludes: Congress’s Role in Assessing any Presidential Obstruction-of-Justice and Abuses of Power and Ensuring Accountability, explains why arguments that he could be are anathema to our constitutional structure. While the president is the head of the executive branch, the Constitution requires that he “take care that the laws be faithfully executed,” and it does not allow him to abuse his presidential powers for his own personal gain. Even those with the most robust views of executive authority don’t argue that the president may interfere with an investigation into his own wrongdoing; they differ from other scholars of presidential powers in believing that only political, not legal, remedies are available for such abuses of power.

Congress, with its investigative and impeachment powers, has the ability to impose such political remedies. Thus it’s Congress’s role, under any constitutionally grounded theory of executive power, to evaluate the president’s motives and, if those motives are improper, take appropriate actions for accountability. Twice in our history, as we recount in When Mueller Concludes: Lessons from Previous Independent Investigations and Related Congressional Oversight, the House of Representatives has determined that impeachment would be the appropriate remedy for presidential obstruction-of-justice.

Trump’s assaults on the facts and the rule of law are dizzying, but at the end of the day, the American people aren’t buying it. A poll from the nonpartisan group, LawWorks, found that nearly 75% of Americans reject the Trump Campaign’s argument that getting opposition research from a foreign government is A-Okay because of the First Amendment. And 83% of voters, including 62% of Republicans agree that “it would be an abuse of power for Donald Trump to try to stop an ongoing investigation of him and his campaign because no one is above the law, not even the president.”

Congress is now in a position to consider how to provide the accountability that the American people believe is appropriate. It can draw on precedent from previous investigations of presidential wrongdoing and, as described by the Supreme Court, “make investigations and exact testimony to the end that it may exercise its legislative function advisedly and effectively.” It should carefully and thoroughly develop a factual record. It must ensure that it receives all of the findings from Mueller’s work and doesn’t allow Trump or the Justice Department to withhold information necessary to fulfill its constitutional oversight responsibilities.  And with due consideration of that record and the myriad political questions Congress is best positioned to weigh, it must assess the remedies available in cases of serious presidential wrongdoingup to, and including impeachment.

Photo of former FBI Director Robert Mueller, special counsel on the Russian investigation, leaving the Capitol on June 21, 2017, by Saul Loeb/AFP/Getty Images.