New research questions whether parties represent low-income interests early on.

• Unlike recent policymaking stages, party campaign platforms rarely incorporate preferences of the poor.

• This finding contradicts normative expectations that parties would enhance representation for disadvantaged groups.

• Democratic parties show strongest bias in states with greater income inequality;

• Republicans' social policy platforms exhibit least responsiveness to low-income interests.

The results suggest persistent challenges to representing less-resourced citizens even at pre-election stages.