Gerrymandering. It allows incumbent to essentially ignore large groups of voters because they've adjusted the district to be primarily their supporters. This, in turn, leads to a question as to whether their legislative approach is actually "representative" of the voters
This is from an article about gun legislation:
"the Center for American Progress (CAP) has conducted a study that examines the most recent elections for every seat in the state legislatures of North Carolina, Michigan, Pennsylvania and Wisconsin. In each state, residents cast more total votes for Democrats than they did for Republicans. Yet, in all four of these places, Republicans currently control both houses of the state legislature."
"Partisan gerrymandering allows these politicians -- who know they will retain majorities before the elections even happen -- to stop listening to the citizens of their state while they pander to the extremes of their base and the special interests who fund their reelection. Just ask advocates trying to address the critical issue of preventing gun violence."
This is from the referenced report:
"Some states have adopted reforms to keep politicians out of the redistricting process, putting independent commissions in charge instead.12 In 2019, the U.S. House of Representatives passed the For the People Act, which would require every state to use independent commissions in drawing federal districts.13 However, Senate Majority Leader Mitch McConnell (R-KY) has refused to bring the legislation up for a vote.14 In the absence of legislative action, partisan map-drawing is still the norm. Furthermore, advances in map-drawing software have made partisan operatives much more effective at drawing districts that skew to their benefit."
the report makes it very clear that it is a both party problem because the point is not that is its republican or democrat, but rather that is "anti-democratic
