One defining feature of the Democratic primary so far has been the party’s leftward turn. In recent debates, candidates have supported policies like offering health insurance to undocumented immigrants, and commenters have warned about the potential electoral penalty of repelling persuadable voters.

Political science research suggests that moderates generally fare better in elections, but much of our current understanding is speculative: There has been little directly relevant data on how voters are reacting in the moment. Are swing voters being put off? Are Democratic voters excited and more likely to stick with their party?

In a recent survey experiment I conducted, the evidence pointed to both these possibilities, but with one pattern much more pronounced than the other.

The embrace of progressivism solidifies support among Democratic survey respondents when thinking about the 2020 general election. But it repels independents, with a negative effect that is stronger and clearer than the signs of enthusiasm generated among Democrats.