G.O.P. legislators, dozens of whom supported overturning the state’s election results to aid former President Donald J. Trump, are moving to change the entire way that judges are selected in Pennsylvania, in a gambit that could tip the scales of the judiciary to favor their party, or at least elect judges more inclined to embrace Republican election challenges.

The proposal would replace the current system of statewide elections for judges with judicial districts drawn by the Republican-controlled legislature. Those districts could empower rural, predominantly conservative areas and particularly rewire the State Supreme Court, which has a 5-to-2 Democratic lean.

Democrats are now mobilizing to fight the effort, calling it a thinly veiled attempt at creating a new level of gerrymandering — an escalation of the decades-old practice of drawing congressional and state legislative districts to ensure that political power remains in one party’s hands. Democrats are marshaling grass-roots opposition, holding regular town hall events conducted over Zoom, and planning social media campaigns and call-in days to legislators, as well as an enormous voter education campaign. One group, Why Courts Matter Pennsylvania, has cut a two-minute infomercial.