Definition
The Local Swing Voter Score predicts how likely a person is to have voted for candidates from both major parties in past state or local elections.
Technical Details
The model was built to target labels generated from the following two survey questions:
In the last ten years, have you ever voted for a Democratic candidate for a state, city, or town race, not including US Senate or House races?
- Yes
- No
- Don’t know or I have never voted in a state or local election
and
In the last ten years, have you ever voted for a Republican candidate for a state, city, or town race, not including US Senate or House races?
- Yes
- No
- Don’t know or I have never voted in a state or local election
Respondents were labeled according to the following rules:
- Respondents who answered “Yes” to both questions were considered to be swing voters.
- Respondents who answered “Yes” to one question and “No” to another were considered to not be swing voters.
- Respondents who answered “don’t know” to either question were excluded from the dataset.
The Local Swing Voter Score was trained on polling data from the Summer 2025 Murmuration poll. We collected 7,721 responses online from registered voters in July and August 2025. The survey used stratified random sampling to ensure national representativeness across age, race, gender, partisanship, education, and geography.
Scores range from 0-100, where higher scores indicate greater likelihood that an individual voted for both Republican and Democratic candidates in state or local elections within the last ten years.
The model was trained using gradient-boosted decision trees. Model features were drawn from the Atlas by Murmuration dataset, which includes demographic (age, race, gender, etc.), commercial, geographic, and vote history information for all registered voters nationally.
We validated the model’s accuracy using a held-out set of 1,352 polling respondents (20% of the original survey sample amongst 6,721 qualified respondents), and whose data was not used during model development. The model achieved an AUC on this test set of 0.630, indicating useful discriminative ability in identifying local swing voters. Further, among individuals with scores in the top 20% of the Local Swing Voter Score, 60% were actual swing voters in local elections, which makes this group 34% more likely to be swing voters than the baseline proportion across the whole held-out set. Of individuals in the bottom 20% of the Local Swing Voter Score, only 31% were truly swing voters, making this group 32% less likely to be swing voters than the baseline proportion across the whole held-out set.
Use Cases
Partners can use the Local Swing Voter Score to identify and mobilize voters who may not be committed to party-line voting in local and state office and ballot measure elections. These voters may be more open to being persuaded by outreach efforts on a particular topic than a committed partisan might be. Layering the Local Swing Voter Score with the Partisan Score will allow targeting of nominal Democrats or Republicans who may be more likely to vote across party lines in a local election if the candidate appeals to them or a major issue at stake is of particular importance to them.
- Identifying likely Republican issue-based ‘defectors’: Let’s say a partner is working in a state legislative race in a competitive district, where the Republican candidate has a long record of opposition to reproductive rights, and the Democratic candidate has been a strong supporter of reproductive rights. They create a segment of voters statewide with low Partisan Scores (20 and below) who are also most likely to be swing voters (Local Swing Voter Scores of 30 and above), and who are also supportive of reproductive rights Reproductive Rights Support Scores of 60 and above).
- Identifying ‘strategic primary voters’ in open primary states: Let’s say a Democratic primary is uncontested for a race a general election a partner is working on, and they strongly prefer the more moderate Republican candidate win the primary. They could segment on voters who have voted in past Democratic primary elections, but who also have high Local Swing Voter Scores (55 and above), with information about the upcoming election and Republican candidates, as well information about the primary rules in their locality.
- GOTV targeting of infrequent swing-voters: A partner running a Get Out The Vote (GOTV) program in a mayoral race to identify voters who could swing the election but historically don't always turn out. They create a segment with high Local Swing Voter scores (55 and above), low-to-mid Municipal Turnout Scores (30-70) identifying the prime GOTV targets.
Targeting Table
The table below shows the score values associated with each decile to help you more easily target using the Local Swing Voter Score nationally. Note: these score cutoffs may be different in your local districts.
| To target the top... | Set the minimum score value as... |
| 10% | 62 |
| 20% | 55 |
| 30% | 50 |
| 40% | 46 |
| 50% | 43 |
| 60% | 40 |
| 70% | 37 |
| 80% | 34 |
| 90% | 30 |
| 100% | 4 |