Democrats are wary of the political perils of impeachment, even as many have concluded that special counsel Robert S. Mueller III’s report offers evidence that President Trump obstructed justice.

Their fears stem largely from memories of impeachment proceedings involving Bill Clinton in 1998, when Republicans ignored polling data that showed voters opposed impeachment and paid the price at the ballot box. They lost seats in the midterm elections, something that is exceedingly rare during a president’s second term, and Clinton’s popularity soared. Today, polling data once again shows the public opposed to impeachment, making Trump’s removal from office improbable. To Democrats, the peril is even greater because Trump is in his first term, and they don’t want to lose the 2020 presidential election because voters felt Trump was unfairly persecuted.

An 1860 congressional report on corruption under President James Buchanan offers a different lesson about the political power of investigating presidential wrongdoings. By uncovering corrupt White House acts, Buchanan’s congressional opponents dismantled his authority and paved the way for a member of their own party to win the presidency during the next election. In short, impeachment isn’t the only way to take down a presidency.

In 1856, Buchanan, a Democrat, won the presidency with 174 of 296 electoral college votes. While these returns suggest Buchanan captured victory comfortably, that was not the case. He carried only five non-slave-holding states, and even his home state of Pennsylvania was hotly contested.