Larry Downing / Reuters

On May 17, 1973, Senator Sam Ervin Jr. opened Senate hearings into the Watergate affair. “It is the constitutional duty of this committee,” he said, to expeditiously investigate allegations that American democracy “has been subverted and its foundations shaken.” Ervin, a Democrat, did not mince words in characterizing the gravity of the accusations leveled against Richard Nixon’s campaign and administration. At stake were “the workings of the democratic process under which we operate in a nation that still is the last, best hope of mankind.”

President Nixon started in a relatively weak position. His misdeeds came to light during a period of opposition-party control, with Democrats able and willing to wield Congress’s investigative powers to the fullest. Prior to the hearings, Nixon enjoyed approval ratings: in the mid-50s among all Americans and well over 80 percent among Republicans. By August 1973, the Watergate hearings had dragged them down to just 31 percent nationally and a paltry 58 percent among co-partisans.

On August 9, 1974, with bipartisan articles of impeachment hanging over him, Nixon resigned.

President Donald Trump has thus far had a very different experience. For the past two years, Republican control of Congress has protected him from the public exposure Nixon and his staff had to endure. Now that the Democrats have taken back the House, the Trump administration will face a challenge from which it has been immune thus far: a far-reaching, aggressive, and highly public investigation of the kind that brought down Nixon.

Trump’s approval ratings stand at 40 percent overall and 89 percent among Republicans. In September 2017, we wrote, “It is tough for a special prosecutor alone to bring down an administration. That feat is more readily accomplished in the court of public opinion, where an opposition-led Congress can rain hellfire and brimstone upon a troubled presidency.”

We believe our argument will soon be proved correct; hellfire and brimstone are imminent.

Special Counsel Robert Mueller’s investigation has picked off a few campaign aides and charged Russian operatives, but it has yet to breach the inner sanctum of the Oval Office. If Mueller follows existing Department of Justice precedent, Trump will remain safe from indictment. A Democrat-controlled Congress, however, will show no such restraint when it comes to the president and those closest to him.

Democratic control will bring two new advantages in the war on Trump. First, congressional committees hold an arsenal of investigative tools that can be called on with only majority-party assent. Chief among them is Congress’s subpoena power—its ability to compel the production of documents or the sworn testimony of witnesses in furtherance of a congressional investigation. That power can be exercised to produce anything from Trump’s much-discussed but as yet unseen tax returns to public testimony from his senior staff and family members (especially those who fit both descriptions). Moreover, due to a 2015 rule change pushed through by House Republicans, most House committees can now issue subpoenas on the authority of the chairperson alone, including three of the committees most likely to go after Trump: Oversight, Intelligence, and Foreign Affairs.

Second, Congress has the power to draw the results of any investigation into the harsh light of public scrutiny. The Watergate hearings were instrumental in bringing down Nixon because they forced Republicans to contend with damning testimony from the president’s closest aides, broadcast in prime time. Only once his approval among Republicans sank into the 50s were GOP congressmen willing to join the impeachment effort. Removing Trump from office before his term expires would require a similar loss of intraparty support. Since Democrats today don’t control the Senate—let alone hold the two-thirds majority required for conviction on House impeachment charges—it’s all the more important for them to erode the president’s base of support before attempting impeachment. Republicans’ impeachment of Bill Clinton increased his approval rating as those on the left rallied around him. Today, Democrats would do well to keep their fingers off the trigger until the president’s approval has begun to crumble.

Congressional Republicans understand the power of public testimony. Representative Kevin McCarthy let slip in 2015 that he believed the Benghazi hearings made Hillary Clinton “untrustable.” Imagine what Democrats could do with hearings into the Trump campaign’s alleged Russian connections, where the prima facie case for misconduct seems significantly stronger.

Of course, the initiation of a full-scale public investigation alongside the Mueller team’s is not without risks. Members of both the Watergate and Iran-Contra special-counsel teams reported difficulties in coordinating their efforts with Congress’s. Prosecutors labor under strict secrecy to limit the premature release of evidence and avoid influencing public opinion. Congress endeavors to do just the opposite. Democrats in the House will have to tame their eagerness to haul crucial witnesses up to Capitol Hill at the risk of tainting Mueller’s work.

If Congress and Mueller can cooperate, though, both stand to gain from parallel investigations. As the Watergate Special Prosecution Force put it in its final report, “In the end, the continuation of public hearings through the summer of 1973 … brought to public attention testimony relating to alleged White House involvement in the Watergate cover-up and other crimes and thereby helped create for the Special Prosecutor’s investigation a base of public and congressional support.”

Whatever risks the Mueller investigation does pose for the president, history suggests that they will be magnified by a Democrat-controlled House. Although the Watergate Special Prosecution Force never indicted Nixon, its findings were transmitted to the House via a grand-jury report that provided much of the basis for the Judiciary Committee’s articles of impeachment.

In one respect, Trump’s position may now be even more precarious than Nixon’s. As former White House Counsel John Dean recalls, Nixon “was forced to quit not because he had lost his support on Capitol Hill, but because he had lost his support at 1600 Pennsylvania Avenue,” leaving him defenseless against Congress. Leaks from inside the White House suggest that Trump already does not enjoy the unqualified confidence of officials in his own administration.

The other side of the coin is that Trump’s base of popular support amongst Republicans may prove more resilient than Nixon’s. Much has changed since the 1970s. All three national television networks carried the Watergate hearings, and there was, by today’s standards, a certain uniformity in their coverage. The same cannot be said of the age of cable TV and the internet. While CNN will run with the Watergate 2.0 narrative, Fox News surely will not. For every website denouncing Trump for high crimes and misdemeanors, there will be another accusing the Democrats of a witch hunt.

Finally, there is the very different political calculus in the present-day Senate. For Mitch McConnell, Donald Trump is a means not just to GOP control of the upper house, but also to conservative dominance of the Supreme Court and the judiciary more generally. It is hard to see what more it would take to persuade McConnell and his colleagues to abandon this president, considering how many damaging aspects of his personality and record are already in the public domain.

Trump has been likened to Nixon from the beginning of his presidency. Now the real test begins. Will the combination of Mueller and a blue House doom him? Or have Washington and America changed so much that a president can withstand repeated allegations that, on his watch, American democracy “has been subverted and its foundations shaken”?

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