The paper examines whether external interference by autocratic regimes in democracies contributes to democratic backsliding. External autocratic interference can function as backsliding promotion and increase domestic anti-democratic actors’ capacities. Where anti-democratic actors are in government, backsliding promotion takes the form of supportive interference, strengthening the backslider government; where they are in opposition, disruptive interference weakens the government and strengthens anti-democratic opposition actors. Differentiating supportive and disruptive strategies also allows me to draw inference on the sender’s objectives: if support systematically coincides with backslider governments, and disruption with backslider oppositions, I argue that senders indeed intend to promote backsliding. I use Bayesian modelling to test both claims. I use V-Dem data to measure democratic regression and the role of anti-democratic parties in government and opposition, and operationalize autocratic support and disruption via autocratic foreign direct investment (FDI) in and sanctions of democracies, respectively. In a two-step analysis, I estimate the (1) effect of anti-democratic government and opposition parties on the level of autocratic FDI and sanctions; and (2) the effect of autocratic FDI and sanctions, conditional on anti-democratic government and opposition parties, on democratic backsliding. Preliminary findings provide support for the argument that autocracies interfere in democracies to promote backsliding, and that they increase backsliding if they do.