If you’ve read special counsel Robert Mueller’s report, there really can be no question that in it he outlined conduct by Donald Trump that was wholly unbefitting a president of the United States and contrary to the nation’s interests. The president can barely conceal his contempt as he continues to stonewall Congress’s legitimate and essential efforts to conduct oversight of his administration.

House Speaker Nancy Pelosi (D-Calif.), meanwhile, has resisted the growing calls for Trump’s impeachment coming from within her caucus; from several of the 2020 presidential contenders; and the literal chants of “impeach” that arose from the crowd as she addressed the California Democratic Party State Convention this past weekend. She insists that before taking such a drastic step, Democrats must build an “ironclad” case.

She’s right. And the party should listen to her.

As leader of the Senate Democrats during President Bill Clinton’s 1999 impeachment trial, I remember all too well the complex and sometimes competing legal and political questions that now confront Congress, and I admire Pelosi’s leadership in the face of increasing pressure. She has argued persuasively that while “nothing is off the table,” proceeding to impeachment right now isn’t what’s best for the country as a whole or, for that matter, the Democratic Party. As she told late-night host Jimmy Kimmel last week, Congress has an obligation to provide Americans with “the facts” relating to President Trump’s conduct, but “when you go down a path like impeachment, which is very divisive, it could divide the country” in a way that is potentially worse than leaving him in office to face voters in the next election.

Clearly, there are differences between the Clinton impeachment and a potential Trump impeachment — one stemmed from a president’s inappropriate personal behavior; the other is about a pattern of conduct involving Russian interference in the last presidential election and institutional obstruction involving fundamental aspects of the rule of law. But there were lessons learned from the Clinton experience two decades ago that still apply today.

The first is that impeachment — a congressional prerogative spelled out in the Constitution but, essentially, a political choice — is a political loser: In September 1998, independent counsel Kenneth Starr released his report referring Clinton to the House of Representatives for impeachment, and a few weeks later, in October, the GOP-controlled House voted to authorize a formal impeachment inquiry. Republicans were convinced at the time that impeachment would help them pad their majority, potentially by dozens of seats, in the November midterm elections. But on Election Day, Republicans lost five House seats — the first time in more than a half-century that the president’s party had gained seats in a midterm. In December, the House impeached Clinton, but by that time Republicans had been chastened by voters, and the stage had been set for what happened in the Senate.

Every Senate Democrat voted against conviction on both of the articles of impeachment presented to us; nearly all Republicans voted in favor. The effort to remove Clinton fell short and two years later, we Democrats took control of the Senate chamber, and I became majority leader.

Pelosi understands that if congressional Democrats get ahead of the public and impeach Trump on, essentially, a party-line vote in the House, but then fail to gain the two-thirds Senate supermajority required for conviction — which is almost certain, given the way many Senate Republicans have bent over backward to excuse Trump’s questionable behavior — they risk making the mistake Republicans made 20 years ago, making Trump the new “comeback kid” and jeopardizing their own 2020 prospects.

It’s true that Clinton’s approval ratings during that time far exceeded Trump’s approval at any point during his presidency — the former president’s approval rating jumped to 73 percent immediately after he was impeached. Yet despite Trump’s low public approval, Americans are still divided on the question of impeachment: A CNN-SSRS poll released Sunday found that Trump’s approval stood at a fairly weak 43 percent, but also that only 41 percent favor impeachment — a significant number, but still far from a majority.

Members of Congress must lead, and at a certain point, their actions can’t be dictated by polls. But they also have an obligation not to plunge us into an event that could further fracture an already bitterly divided country, something an impeachment showdown risks if Congress can’t persuade the public — not just Democrats — that it cannot be avoided.

The second lesson is that these deeply polarizing clashes have taken an enormous and lasting toll on Congress’s credibility, and the country won’t be able to address challenges ranging from health care to infrastructure, no matter who is president, if the institution’s standing further erodes. We might not agree about when the current atmosphere of hyper-politicization became entrenched — Judge Robert Bork’s Supreme Court confirmation hearings, Bush v. Gore, the Iraq War, Obamacare — but there’s little argument that the environment worsened significantly during the Clinton impeachment. Speaker Pelosi has been a member of Congress throughout and knows better than anyone how these fights have made it nearly impossible for Congress to work together to do the people’s business.

A Senate trial that ends with Trump still entrenched and something like half the country saying, in effect, I told you so, might irreversibly sink public trust in Congress and, ultimately, its ability to govern.

Former senator Trent Lott (Miss.), the Republican majority leader at the time of Clinton’s Senate trial and my co-manager, deserves great credit for maintaining the civility and decorum that the Senate demonstrated throughout the trial. That experience built a trusting relationship between us that allowed us to navigate many more critical issues in the years that followed. It actually created a friendship that lasts to this day. But our personal cooperation in the Senate chamber wasn’t enough to stop the erosion of Congress’s reputation: Right after 9/11, when the country had to come together, Congress’s approval rating rose above 80 percent. In the intervening years, though, with purely partisan squabbles, abuse of the filibuster, the advent of social media, too much money in politics and members spending too little time in Washington getting to know each other as people and as Americans, not just adversaries, that rating has fallen, seemingly for good, to around 20 percent.

We’re a year-and-a-half away from the next election. Given the virtual certainty that, even if the House impeaches, the Senate won’t convict, a more prudent course of action is called for on the part of congressional Democrats.

The House should continue to use all its constitutional and legislative powers to conduct aggressive oversight, including a comprehensive review of everything in Mueller’s report, the president’s tax returns and financial records — Americans deserve a clear and complete accounting of these findings before they are called upon to vote next year.

And Democrats should approach 2020 understanding that Trump has something like a 50-50 chance of winning reelection, rather than acting like impeachment is just an acceleration of the inevitable. Pelosi says impeachment has a “silver lining” for Trump, because she understands that if he’s impeached but not convicted, “he believes he would be exonerated,” and Democrats would be demoralized. We can’t afford the confusion such an outcome would create. At stake is the fabric of our republic: our democratic institutions and the rule of law.