Readers often ask me “What’s one Senate race I need to watch to know which party is going to end up with control of the chamber?” There are two honest, different, and yet compatible answers to this question.
The first: There’s no one race that will decide control of the Senate because it’s all a little bit like whac-a-mole. The map features multiple competitive races, and either party could make up for a loss in a “pivotal” race with a win in another race.
The second: If you must pick just one race to watch, you should probably pick Tennessee.
Why Our Model Thinks Tennessee Is Important
In Sunday night’s run of SwingSeat (THE WEEKLY STANDARD’s daily updated stats-driven Senate forecast), I decided to calculate a statistic that you might have seen in other places (like the New York Times, FiveThirtyEight, RealClearPolitics or Cook Political Report): the tipping point probability. The tipping point probability for a given state (in the context of the Senate) is the chance that it’ll give the winning party the final seat that they need to clinch the majority. So if Republicans win 50 seats in a given simulation, the tipping point state is the one they won by the smallest margin. If they win 55 seats in some other simulation, the tipping point would be the state that (when ordered from greatest to smallest GOP margin) gets them their 50th seat (the other five are wins above and beyond what they need for a majority). And in a simulation where the Democrats take the Senate, the tipping point state is the state that gets them to 51 seats (Republicans can get a majority with only 50 seats because Vice President Mike Pence would break ties).
In the latest run of the model, Tennessee was the most likely state to be the tipping point. Tennessee wasn’t objectively likely to be the tipping point state. The odds were less than 1 in 4, and Arizona, Nevada, Missouri, Texas and North Dakota all had a real chance of being the 50th vote for the Republicans (or the 51st vote for the Democrats).
Intuitively it makes sense that Tennessee is high on the list of plausibly pivotal states. Ted Cruz’s lead in Texas seems to be solidifying. The last few polls in North Dakota show Kevin Cramer, the Republican candidate, with a double digit lead. Winning those two seats plus Mississippi’s Special Senate election and the safe red states puts Republicans at 49 Senate seats. According to our model, Tennessee is the next most likely Republican win. That means that in a solid number of scenarios, it’ll end up being the GOP’s 50th seat or the 51st Democratic seat.
Not every simulation looks like this (in fact, a large majority of the scenarios don’t even have Tennessee as the tipping point state) and there are other caveats here (e.g. different models will get different tipping point probabilities, I had to make a couple judgment calls about how to handle Mississippi’s Special Senate race, etc.). But the overall point is clear – Tennessee is arguably as close or closer to the “middle” of the map as any other state.
Marsha Blackburn: Still Competitive But Gaining Speed Fast
The basic lay of the land in this race is relatively simple. Representative Marsha Blackburn is the Republican candidate. Her voting record is strongly conservative according to quantitative measures like DW-NOMINATE, and she’s been a Trump ally for some time. Her opponent is Phil Bredesen, the state’s former governor. Bredesen has tried to argue that he would be a moderate problem solver (e.g. he said he supported Brett Kavanaugh’s nomination) who would be able to represent a deep red state despite his party label.
And that’s about it.
My colleague Mike Warren recently went to Tennessee and did some great reporting on this race: He found that political identity was central to this race and that ideas and issues took a backseat. And this race has been unfolding essentially how one might expect an political-identity-driven race to pan out.
This graphic shows the trend in SwingSeat for Blackburn. The “full” model uses fundamentals like presidential approval, past election results, incumbency and the fact that it’s a midterm along with polling data to project the results of the race. That’s our official model. And the “Just Polls” version represents an older iteration of the model that uses polls and basically nothing else to project the results. The trend shows how her win probability has evolved over time in both models.
Both projections showed a close race for the last couple of months. That dynamic made sense, because Bredesen is a former two-term governor and so would be likely to start out ahead of where a more generic Democrat would start out.
But about 40 days before Election Day, Blackburn began to really gain steam. Part of the movement is likely the result of the Kavanaugh hearings. Tennessee is a red state, so increased Republican enthusiasm for Kavanaugh may generate net votes for Blackburn (i.e., if pro-Kavanaugh sentiment energized Republicans and anti-Kavanaugh sentiment energized Democrats, the overall math might favor Republicans in a state as red as Tennessee).
But Kavanaugh may not be the whole story. The race might have headed in this direction even if Anthony Kennedy hadn’t retired and Kavanaugh had never been nominated.
I did a “fundamentals-only” projection of this race—I basically asked the model to look at the Tennessee only using non-head-to-head polling factors. There are a lot of ways to generate fundamentals based forecasts (e.g. I don’t use fundraising data in mine and others do), and different methods will produce different results. But my forecast suggests that the Republican in this race should be at least a 2-to-1 favorite (in terms of odds) in a race like this one.
Moreover, Trump’s approval rating was a net 20 points more positive than negative in September’s Morning Consult survey. If we assume that Bredesen is a solid candidate who could convince a modest chunk of Trump supporters to back him, you might arrive at something like the high single digit lead that Blackburn enjoys now.
Put simply, this race might be heading towards the sort of outcome that non-polling factors suggested all along – a strong but not unbeatable Blackburn advantage.
That puts Marsha Blackburn in sort of a Hillary Clinton zone—the major indicators favor her and she has a real advantage, but it’s not a large enough advantage to rule out an upset. Candidates who are in this zone really do win much more often than they lose, but (maybe obviously after 2016) it’s not a guarantee.
And stubborn races like this are part of the reason that the GOP’s overall win probability has been hovering at around 80 percent in our model. Blackburn is very much the favorite in this race. But she, like Texas Sen. Ted Cruz and (to a lesser extent) North Dakota Rep. Kevin Cramer, haven’t yet totally put away their opponents. They’re all real favorites in their respective races, but they’ll all have to keep plugging away through Election Day.
