Starting in 2017, the NBC/WSJ poll has tracked two types of key Trump Counties in competitive states: Trump Surge and Trump Flip. The Trump Surge counties are those where Trump outperformed Mitt Romney’s 2012 net vote percentage by 20% or more. And, the Trump Flip counties are the counties that flipped from voting for Barack Obama is 2012 to Donald Trump in 2016.

By using merged data from all registered voter interviews from the NBC/WSJ poll (N=9,180 total interviews in 2018), it allows us to look at these key counties. After controlling for demographic differences between years, Trump has maintained and solidified his position in both of these county types.

In the Surge Counties – where Trump ran up large margins in the 2016 election – the President’s approval has passed the 60% mark, with an approval rating of 62% approve-31% approve. This is an improvement over his 58%-33% rating in the 2017 data.

And in the Flip Counties, Trump’s approval stands at 47% approve-51% disapprove, modestly up from 45%-50% in 2017 NBC/WSJ data. At the same time, registered voters’ feelings towards the President remain unchanged at 39% positive in 2018 compared to 40% positive in 2017. (Trump was elected with a 31% positive-57% negative image in these counties that he flipped in 2016 – this is a marked improvement over his standing then.)

At the same time, the Republican Party’s image in these Flip Counties has improved from 32% positive-47% negative in 2017 to 34% positive-40% negative in 2018. This paired with the Democratic Party being slightly less positive in these key Flip Counties at 33% positive-42% negative, helps show that these counties will remain competitive and could still lean GOP lean in 2020.

With President Trump improving over 2017 in the Surge Counties where he needs to run up his vote margins, he does not need to win every single Flip County in 2020. And, given that his approval in these Flip Counties is stronger than his national job approval (44% approve-53% disapprove in the merged NBC/WSJ 2018 data), it is important to remember that the 2020 election will be decided in these counties and not the parts of the country steadfastly against President Trump.

Polling for NBC News and The Wall Street Journal is conducted by Republican pollster Bill McInturff and Democratic pollster Fred Yang. This analysis is my own and does not necessarily reflect the views of NBC, The Wall Street Journal, or Hart Research Associates.