While Kamala Harris is riding a momentum wave in polling that puts her slightly ahead of Donald Trump in most places, one element trending against her is the battleground states partisan registration gap.
Only 30 states’ voters register by political party designation, and several of them are in the most competitive category. Arizona, Maine, Nebraska, Nevada, New Hampshire, New Mexico, North Carolina, and Pennsylvania, all of which are either hotly contested or showing signs of potential swing voting, require partisan registration designations on the voter registration forms. (Maine and Nebraska are included here because they split their electoral votes, meaning allowing each congressional district to carry its own vote. Both states have districts that tend to swing opposite of the statewide tally.)
In some cases, both parties have less members in these swing domains than they did in 2020, largely due to the election authorities conducting list purges to eliminate people who no longer live at the stated address, have passed away, or have not voted in a specific number of consecutive elections (state laws differ on the criteria listed last).
All of the aforementioned states have less registered Democrats than they did at the beginning of 2021. Arizona, North Carolina, and Pennsylvania show a greater number of registered Republicans on their most recent registration report as opposed to where they stood at the beginning of 2021. Arizona, Nevada, North Carolina, and Pennsylvania also have more unaffiliated voters than they did at the beginning of 2021.
The statistic of particular interest comes in the states where the raw number registration gap between Democrats and Republicans has significantly changed. It is here where the Republicans benefit substantially, and this is a statistical category that will not necessarily be reflected in polling.
In Arizona, New Hampshire, which is a new entry in this category, and the 2nd District of Nebraska, Republican registrants outnumber Democrats. New Hampshire flipping to plurality Republican since 2021 could signal a different vote pattern in 2024, and that could make a major difference in several races including the presidential campaign.
If Mr. Trump were to convert Arizona, Georgia, Nevada, and New Hampshire, while assuming he kept all 25 states and the 2nd District of Maine in his column, all of which have voted for him twice, he would win a 272-268 electoral vote victory, and can do so without carrying any of the key Great Lakes states that are typically highlighted as the deciding factor in the national race.
In all of the remaining swing or potentially swing domains: Maine, Nevada, New Mexico, North Carolina, and Pennsylvania, Democrats still outnumber Republicans, but the registration gap between the two parties is much smaller denoting Republican gains in each place.
Most significantly, in three states, Arizona, Nevada, and New Hampshire, the net Republican registration gain is larger than the number of votes that separated Joe Biden and Donald Trump in the 2020 election. Therefore, these states become obvious Trump conversion targets.
The Republican registration gap in North Carolina has also improved for the party. Though still behind the Democrats by over 132,000 registrants, the new numbers represent a net GOP gain of 111,066 individuals than at the beginning of 2021. Therefore, while Mr. Trump twice carried the Tar Heel State, his margins were small and the boost in registration should make this critical state a bit safer for his Republican team in 2024.
The state of Florida is the most extreme registration change example and is generally what takes the state out of play not only for Democrats at the presidential level, but also in the US Senate race between incumbent Rick Scott (R) and most likely former US Rep. Debbie Mucarsel-Powell (D).
Since 2021, the registration gap has grown in the Republicans favor by a net 940,005 individuals, which gives the Republicans a registration advantage over the Democrats of just over 1,000,000 partisan voters.
While polling detects the Harris surge in the presidential race, the Republicans closing the registration gap in all of the battleground states where registered partisanship can be measured should be considered at least one significant neutralizing factor of the polling numbers as we head toward early voting month in October.
We offer this political insights report for your information and not as a predictor or representative of opinions of HBS or its employees.
