No, Trump and the GOP Are Not Immune from the Rules of Politics

I was having drinks with a friend last night and we got to talking about the political situation, as we are wont to do. Like most liberals I know, he'd been tracking the precipitous fall in Trump's approval ratings and speculating that this could really help the Democrats in 2018 and beyond. But also like most liberals I know, he caught himself after a bit and allowed as how, after 2016, he really has no confidence that what seems like it should hurt the GOP actually will. We just live in a different universe now and the old rules don't apply. 

I get why people think that. But do we really live in such a different universe today? Harry Enten has a very useful article up on 538 today, buttressed by considerable data, that argues the general rules still apply and we'd be silly to think anything different. Enten argues:

The available evidence…suggests many of the old rules do still apply. Caution…is more than warranted, especially given Trump’s history of surprising analysts and pundits. Partisan polarization has increased, and there is plenty of time for Trump’s approval rating to improve. But caution is one thing; ignoring history and evidence…is another. And the idea that “the normal rules of politics don’t apply to Trump” strikes me as the latter — at least according to the data before us. Early signs suggest that Trump’s low approval rating is having exactly the negative effect on down-ballot Republicans that history would predict.

Midterm elections are often thought of as referendums on the sitting president. When there’s been an unpopular Democrat in the White House, voters have swung toward Republicans in congressional races. With a struggling Republican president, voters swing Democratic. You can see this by looking at the effect a president’s approval rating has on the national House vote. Specifically, we can look at how much the national House margin would be expected to shift from the previous presidential election based upon the president’s approval rating right before the midterm election.

In 2004, for example, Republicans won the national House vote by 3 percentage points. But two years later, in 2006, with President George W. Bush’s approval rating at 38 percent, Republicans lost the House vote by 8 points — a 11-point swing from 2004.

It’s far from perfect, but in midterm elections since 1946, there’s a clear relationship between the president’s approval rating and the swing in the House vote.

Trump’s current approval rating is 38 percent. Historically, we would expect a president that unpopular to cause his party to lose around 11 points off its previous House margin. Republicans won the national House vote by 1 percentage point in 2016, so this suggests they would lose it by 10 points if the midterm elections were held today.

Other data support his argument:

[T]he generic congressional ballot, a common poll question that asks respondents whether they will vote for the Democrat or Republican in their congressional district. Democrats right now hold a 46 percent to 37 percent lead, according to the FiveThirtyEight aggregate. That’s a bigger lead than Democrats had at any point in 2016 cycle, and it’s in line with the margin necessary for Democrats to take back the House.

There have been 30 special state legislature and U.S. congressional elections since Trump was sworn-in as president. Democrats, as a group, have been outperforming the partisan lean in these districts — tending to come close in ruby red districts, winning swing districts and romping in light blue districts. More specifically, Democratic candidates have done about 16 percentage points better, on average, than you’d expect in a national environment in which no party held the advantage. (Imagine a world in which the Democratic and Republican presidential candidates tie 50-50 in the popular vote). This overperformance holds as well for the smaller subset of congressional elections.

 So quit being so paranoid. No guarantees on outcomes of course, but you can have confidence that what looks bad for Trump and the GOP is bad for Trump and the GOP.