Democrats are riding a wave of anti-Trump outrage into the 2018 midterms, while Republicans find new ways to describe their discomfort at President Trump’s long, public breakdown.

Beyond that, historical precedent already puts the party in the White House behind the 8-ball. The House has changed parties four times since World War II: 1954, 1994, 2006, and 2010. All four were midterm elections where the president’s party lost control.

If that trend holds, Democrats will re-take the House, probably by a wide margin. And if that happens, it’s a safe bet that impeachment will follow. In fact, I wouldn’t be shocked if the first thing a newly Democratic House does is take a vote to authorize the House Judiciary Committee to begin an impeachment investigation, especially if Special Council Robert Mueller’s final report recommends it.

That’s when the chaos really starts, and Republicans will have to make some very difficult decisions about the 2020 election.

Impeachment is rare enough that each case has its own story. Richard Nixon’s impeachment dragged on for nearly a year, as it was October 1973 before Judiciary began even considering impeachment, with hearings not commencing until May and the committee voting in July to approve three articles. Nixon resigned weeks later.

But when Bill Clinton was impeached, the timeline was greatly compressed. Using Independent Council Kenneth Starr’s report, which had been submitted to Congress in September 1998, House Judiciary voted a month later to begin hearings. There was no investigation, and the articles were approved in early December, with the full House voting just weeks later. Clinton was on trial in the Senate just after the first of the year.

If the House Judiciary Committee takes up the impeachment of Donald Trump, chances are that it will follow the Clinton timeline rather than the Nixon one.

Democrats likely will have Mueller’s final report on Trump’s collusion with Russia at their disposal. If Mueller goes the way Starr did (Starr found 11 impeachable offenses, four of which became articles of impeachment), he’ll present it to Congress, and leave it to them to deal with the fallout.

Assuming Democrats begin the impeachment process, it will likely come to fruition around late spring or early summer. As it happens, that’s about the time presidential candidates start announcing they’re running.

Remember when Trump rode that gold escalator down into history? It was June 2015. Four years later, it’s entirely possible Trump will be preparing for or undergoing a trial in the Senate to decide the future of his presidency, even as he begins the process of announcing a run for a second term.

How on earth does that work?

What happens if he’s impeached but not removed? Will Trump announce a re-election campaign despite having his current term endangered? How do Republicans react to Trump standing at the edge of the cliff and looking down into either removal or being the first president in modern history to be impeached in his first term? Do Republicans run a parallel campaign to primary Trump, or to ensure someone can run if he’s removed or resigns? Do they beg him not to run again? Make a deal with him?

And what if he IS removed? It’s not likely, given that it takes 67 votes to do so. But it’s possible. Does Mike Pence announce a run, or ride out the rest of Trump’s term as a caretaker? What Republican even has the credibility to pick up the pieces?

These questions might seem a long way off and entirely theoretical. And that’s not to say that Democrats should make 2018 entirely about impeachment. In fact, right now, they shouldn’t.

But all of that could change with Mueller’s final report and further indictments. If 2018 is all about the midterms, and the midterms suddenly become a referendum on impeachment, and impeachment suddenly becomes a reality, they’re going to be the only questions anyone will be asking. They have no easy answers, no historical precedent, and are fraught with danger.

Pass the Tums.