Will Donald Trump cause the GOP to lose Congress?

While Donald Trump's campaign spirals around firing wantonly and GOP elites run for cover, the presidential election understandably overshadows the other elections coming up in less than a month. Meanwhile, the GOP is in a tense battle to maintain control of the Senate, and GOP leaders are increasingly worried about maintaining what was previously seen as a secure majority in the House.

Trump is causing headaches for the GOP during a highly contested electoral cycle; this isn't news. What is news, arguably, is how these troubles are reverberating through the various elections across the country. After all, if Trump hinders the Republican Party across all congressional races in a relatively uniform fashion, then it would be easy to dismiss this cycle as an unfortunate occurrence that might be temporarily costly to the party but can otherwise be dismissed as "just a Trump effect." (I'll just leave that phrase there.) On the other hand, if the Trump effect varies across different states and electoral races, then it might represent a longer-term shock to the GOP's electoral base.

Accordingly, let's dissect how Trump is affecting the battle for Congress and, more speculatively, what this means for the GOP looking out a few years into the future. Thinking in terms of states, illustrations of the Trump effect can be broadly broken down into three categories, which I will refer to as "complicating matters," "bad mojo," and "uh-oh." Let's turn to considering these categories in turn.

Complicating matters

Trump's troubles in swing states, such as Florida, North Carolina, Ohio, and Pennsylvania, are widely and frequently discussed. The GOP's congressional challenges in those same states are not surprising: These are "swing states" because their citizens are closely divided in partisan terms. Put another way, Paul Ryan and Mitch McConnell were expecting to have hard fights here even when they thought Jeb Bush was going to be the nominee. If the Trump effect sinks some or all of these races, it's a cost, but it's not out of the ordinary.

Bad mojo

While the Trump campaign's problems in Utah are admittedly surprising, the GOP is doing fine otherwise in the state. In Utah, incumbent Republican Sen. Mike Lee is solidly leading his Democratic opponent, Misty Snow. Similarly, all four of Utah's incumbents are from the GOP and electorally safe this cycle. Thus, Trump losing Utah is a problem for Trump, and Trump alone. As Ryan has effectively already cut bait with respect to Trump, states like Utah are, at worst, "acceptable casualties" on the GOP's multifaceted battlefield in 2016.

Uh-oh

Missouri provides a clear picture of the GOP's currently unfolding nightmare. First, Trump is currently solidly winning the state. From a GOP perspective, take that as you will. Second, and more importantly, incumbent Republican Sen. Roy Blunt is currently in a very tight race with his Democratic challenger, Jason Kander.

This is an "uh-oh" for the GOP because the Missouri Republican Party has a broad and safe base in the state. That is, Blunt's seat was considered "safe" at the beginning of the cycle. A loss here is not "just a loss" but a loss of a secure seat in a relatively populous swing state. Put bluntly, a loss by Blunt represents a sharp cut to the GOP's position in Congress.

On its own, the fact that Trump's campaign is currently struggling in the electorate at large but still leading in Missouri does not mean much. But the fact that the GOP might somehow secure a win for its "outsider" presidential nominee while also losing a secure Senate seat held by an establishment incumbent does mean a lot. Actually, it means a whole lot. 

It means, potentially, that the GOP leadership has truly lost touch with its base. If the GOP leadership, thrown into a crisis arguably of its own making, can't corral sufficient unity to secure Blunt's reelection in Missouri, then the rules of the game have changed. It means, in particular, that some classically Republican voters are voting for Trump but not voting for the Republican Party.

Furthermore, history suggests that presidential performance (or "coattails") should essentially affect only "marginal" congressional races. That means, in practice, that when, say, the GOP has an unpopular presidential nominee, then Republican congressional candidates perform below average in those states in which the Republican nominee also performs below average. Something like a "sinking tide lowers all boats" effect, as one would expect from an electorate largely composed of party-line voters.

In Missouri this year, on the other hand, contrasting the current polls for Trump/Clinton with those for Blunt/Kander indicates an "inversion" of the historical experience. Specifically, in spite of relatively solid support for the top of the GOP ticket (Trump), Missouri voters appear to be moving more strongly against the incumbent and relatively popular Sen. Blunt. While Trump is seemingly sailing smoothly in Missouri, his (immediately) "down-ballot" companion is in the fight of his electoral life. This is an inversion: The top of the ticket is doing well, but the down ballot is suffering.

What does this inversion for the GOP mean?

Of course, everything is up in the air through November 8. That said, the polls right now suggest that the Republican Party leadership (ahem, Paul Ryan) has a serious reason to worry about Trump's effects both down ballot and into the future. While control of the Senate in 2017 is presumably important with respect to Justice Scalia's successor on the Supreme Court, incumbency is a powerful (but not almighty) force — if the Democrats gain seats in the Senate and the House, then the 2018 election is a much more difficult cycle for the GOP. (Though, to be clear, the Democratic Party will have more seats "in cycle": 21 of 33, with independents Angus King of Maine and Bernie Sanders of Vermont caucusing with the Democrats as well, bringing the effective total to 23 of 33.)

This is a very, very weird election. But US history to date suggests that weird elections are, in fact, weird in the sense of not offering much insight into the next cycle. That goes to say that Trump, even if he loses, probably won't "destroy" the GOP. After all, the next national election cycle in 2018 won't have a presidential race. On the other hand, that's precisely why Trump's effect on this year's congressional races should frighten GOP leaders. Particularly for the Senate, it's harder to regain seats than to defend them.

This post is part of Mischiefs of Faction, an independent political science blog featuring reflections on the party system. See more Mischiefs of Faction posts here.