Now that Robert Mueller has broken months of silence, declined informal invitations to appear before Congress and said his 448-page report “is my testimony,” it now falls to lawmakers to take the next steps, if any, in the matter of President Trump. House Speaker Nancy Pelosi, D-Calif., has been hesitant to initiate impeachment proceedings against Trump. Her caution is well placed.

Impeachment is an extraordinary political remedy under the Constitution. The democratic process by which we elect a president is defined by passion and partisanship, but any effort to remove that leader is likely to be unsuccessful if it is similarly motivated. As an English lord chancellor once wrote, “The power of impeachment ought to be, like Goliath’s sword, kept in the temple, and not used but on great occasions.”

William S. Cohen Associated Press photo

All who are elected or appointed to high office are fiduciaries of the public trust. Supreme Court Justice Benjamin Cardozo once described the standard of a fiduciary’s conduct to be “something stricter than the morals of the marketplace. Not honesty alone, but the punctilio of an honor the most sensitive.”

With the exception thus far of Rep. Justin Amash, R-Mich., Republicans have taken the position that Mueller’s redacted report has resolved all issues of alleged presidential collusion with the Russians and obstruction of justice. Case closed.

This is not a tenable position. The Mueller report has raised nearly as many questions as it has answered. But more important, as someone who legislatively helped craft the original Office of Special Counsel, I can attest that Congress never intended to subcontract out its investigative powers to the executive branch.

Congress can be informed by, and take advantage of, Justice Department or special counsel investigations, but it should never be limited by them.

At the moment, public opinion polls indicate that a majority opposes impeachment proceedings against Trump. It also appears unlikely that two-thirds of the Senate would support removing the president from office based on the evidence currently available.

Politicians who ignore public opinion do so at their peril, but peril goes with the territory of holding office. It’s also important to remember that public opinion is not anchored in concrete. It shifts according to the information it finds to be persuasive and free of rank partisanship.

During the Watergate scandal, the majority of the American people initially opposed impeachment proceedings being launched against President Richard Nixon.

But as the hearings moved forward, we learned that, among other activities, the president had authorized the payment of “hush” money to those who had engaged in criminal activity, urged his subordinates to commit perjury before Congress, attempted to have the CIA derail an ongoing FBI investigation, and sought to use the IRS to punish those on a list of his political enemies.

In our private deliberations, the majority of Republican members of the House Judiciary Committee at the time divided into those who strongly opposed the effort to find impeachable conduct whatever the facts, several members who indicated they were open to persuasion if the evidence was clear and convincing, and a few who held their cards very close to their vests.

Democratic members seemed divided between those who were strongly in favor of impeachment and those who had to be persuaded – among the latter were those from Southern states where Nixon had strong support.

In the end, six Republicans nonetheless felt compelled to place loyalty to the rule of law above our political affiliation and political futures. We concluded that Nixon clearly had engaged in obstruction of justice and abuse of power.

The silence of Republicans today in the face of presidential behavior that is unacceptable by any reasonable standard is both striking and deeply disappointing.

When one talks privately to some Republican members about a president who lurches from tweet to taunt; who, according to those who have worked closely beside him, is incapable of telling the truth even in mundane situations; who accepts the word of President Vladimir Putin and rejects the unanimous judgment of our intelligence community that Russia launched a cyberattack at the very heart of our democracy; and whose toxic combination of egotism and insecurity distorts the basic process of governing, they express their disdain and even alarm at how he conducts the nation’s affairs.

Yet, the same members are reluctant to speak out publicly even in the face of behavior they would find intolerable by any previous occupant of the Oval Office.

Fear is a potent weapon. Today, Trump uses the accelerant of social media to rally and stir the passions of his supporters, even with information that is patently false. Technology’s ubiquity, speed and power, and other profound changes, make this a more complex time than the Watergate era was.

But Congress should not turn away from the central issue of whether Trump has, in word and deed, engaged in conduct that is fundamentally inconsistent with, and antithetical to, the highest office in the land.

If Congress cannot secure the cooperation of executive branch officials in the exercise of its oversight responsibilities, it will have no choice but to enter the temple and remove the fabled sword.

William S. Cohen represented Maine as a Republican congressman and senator, and later served as defense secretary. He was a member of the House Judiciary Committee in 1974 during the Watergate impeachment inquiry.