Partisan lean of swing states since 2004
There has been much discussion about how Pennsylvania is the most likely "tipping point" state in 2024. While it seems fairly unlikely, there is a case to be made based on historical voting trends that a candidate may be able to win the 2024 race without winning PA.
Here's a plot of the partisan lean* of 5 key swing states since 2004.
While PA has consistently leaned more towards the Democratic candidate than GA and AZ, the gap has closed enormously since 2012. PA's shift right stalled in 2020 while AZ and GA continued to shift left. If this trend continues, GA and AZ could move to the left of PA in 2024.
Of course, there is no guarantee that the trends of the past two cycles will continue in 2024. Importantly, the polls aren't necessarily showing GA and AZ moving to the left of PA. This seems to be particularly true in AZ where border concerns and decreasing support among Latino voters appears to be a bigger issue than in PA.
A couple additional observations:
- All 5 of these state leaned right in 2020, though Biden won 4 of them because he won the national vote by 4.5%.
- Interesting to me that NC is the only swing state which hasn't really shown much shift in partisan lean since 2012. Most polls show that Harris has a better chance of winning NC than GA or AZ this year. If so, that would represent a fairly significant shift for NC since the 2012-2020 era.
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*Partisan lean is the difference in vote for a state compared to the national vote. For example, Biden won MI by 2.8% and the popular vote by 4.5%. This represents a 1.7% partisan lean towards the Republicans for Michigan. For the purposes of this graph, a positive value means that the state leaned more toward the Democratic candidate than the national vote and a negative value means that the state leaned toward the Republican candidate.