That said, it’s not guaranteed that even clearcut legal violations will seriously undermine a presidency. Back in 1998, polls found that Americans thought Bill Clinton had lied, and even obstructed justice, but that wasn’t enough to get them to support removing him from office. There appears to be some room for presidents to break the law, as long as people are happy with the direction of the country in general, or perceive the other side as worse. Trump has also tried to downplay the importance of campaign finance laws. It’s not clear that this strategy will work. But many Americans think that money in politics is already a problem, so violating the laws in place might not damage legitimacy that much beyond existing levels of disgust with the system.
Trump, of course, isn’t Bill Clinton. He’s more unpopular, and that could make a big difference. In August, 1998 (about a month before the House Judiciary Committee began considering impeachment articles), Clinton had net approval rating1 of about +30 percentage points, according to FiveThirtyEight’s approval tracker. Right now, Trump has about a -12 point net rating. Clinton’s popularity helped reinforce his claim to the presidency even as it became clear he broke the law. It helped to keep Democratic officials from breaking ranks, for example. Trump doesn’t have that shield at the moment.