The existing model of political competition is extended to allow voters to
live in different regions and to migrate between regions in response to an
inter-regional transfer policy. We then show that regions have a different
"weight'' in the expected vote function of political parties. This gives pa
rties an incentive to bias the transfer policy in favour of relatively high
weight regions, with potentially adverse efficiency and equity effects. Ho
wever, we then show that parties always propose efficient and equitable reg
ional transfers, regardless of whether regions have different weights, if t
here is some mobility of citizens across regions. Mobility constrains parti
es to act efficiently and equitably even though they face an incentive to a
ct otherwise. However, when voters are immobile political competition leads
to inequitable though efficient outcomes.