In the latest NBC/Marist poll, Democrat Joe Donnelly leads 49-43 in a head to head, but his lead falls to 44-41 when the Libertarian takes 8% when included. In this thread, I hope to explain why that is and what you can expect in November (1/a lot) https://www.nbcnews.com/politics/first-read/nbc-marist-poll-democrat-joe-donnelly-has-slight-edge-indiana-n906851

To start with, let's take a look at the shifting population within Indiana, starting with this map showing the numbe rof people by county. The population is fairly spread out, but concentrated more in the North and Central portions

In recent presidential elections, the % of voters coming from the smaller counties (less than 30k) voters has steadily declined as the large counties (>80k) have picked up a larger share of the votes

Historically, third party performance has been both weaker in the main central counties and in the more rural Southern border, reflective of lower performance in both the cities and Appalachia that shows up nationwide

In 2016, however, third parties were higher in all the higher populated areas, especially the central city of Indianapolis and the suburbs, where before it has been normally low. It is also higher by Gary and South Bend in the Northwest

2016 is a standout for another reason. The chart below shows the % of the share of the 3rd party vote in the county size groupings minus the share of the electorate. For example, if 30% of 3rd party votes and 25% of the electorate is small counties, that would be 5%

This shows that recently the 3rd party share had been coming from the smaller rural areas, but in 2016 where third parties were outsized in large counties, which was the highest in the modern era over 2000 (an even 0% difference that year)

Now, we can look at its impact on the presidential margin shift from 2012 (left), with red moving towards Trump and blue towards Clinton. The map on the right shows the impact and a combination of whether 3rd party was up or down, and which direction the margin moved

Here you can see the difference of 3rd party on the margin and the shift left in the central counties vs. its weaker impct in the Northwest

This plots out the relative third party perfroamce vs. historical performance on the x-axis, and the margin shift from 2012 on the y-axis, with positive moving towards the Republicans and negative towards the Democrats

You can see the population size division but also the correlation that as third parties did better, the margin moved towards the Democrats and vice versa

So now we see that the 2016 third party vote are likely GOP deserters in high population areas, a key area to focus on in a close race and also the deciding factor in races like Virginia governor

The only real third party in Indiana is the Libertarians and they consistently run candidates in elections. The plot below shows their share in major races since 2000, with an explosion of growth starting in 2010 and staying high since then, even in close races, like 2016 Senate

In 2016 Senate and now in 2018, the Libertarian candidate is Lucy Brenton, a former Miss Indiana and business executive who ran for the City Council as a Libertarian in 1995 and is currently the Hamilton Libertarian chair http://www.lucyforsenate.com/who-is-lucy/ 

W/ her 5.5% statewide vote in 2016, she will be in the debates. She may take from both sides as her policies are a mix of pro-life, pro-gay rights, pro-environment and anti-tax. Outside groups could promote aspects of her record to win over certain people, a la 2014 NC Senate

Well well-spoken, in the one interview I could find, she espoused views outside the mainstream, specifically that vaccines are causing transgenderism and homosexuality at a young age, which may come up if the party wants to prevent spoilers

In 2016 Senate, even though it was supposed to be a nailbiter, she did take 5.5%, with her share much more concentrated in the Northeast and Central portions

This is more unique, especially in the North, as Brenton outperformed the 2012 Libertarian nominee Andy Horning in the North while falling behind in the center, and they both got about the same share statewide

That Northeastern portion is also where Donnelly typically perfromed better that past Democrats in the Senate race, mostly because he represented the North central South Bend district while in the House

Brenton will likely fall a few % points but could definitely force a plurality win. The new Brenton coalition of North votes + the Gary Johnson suburban vote that is flirting w/e Dems means that they likely have Donnelly as 2nd choice, and he'll need to work to get them /end