Actually, I would argue they managed to win/retain power in part, if not mostly, because of gerrymandering and voter suppression strategies.  A judge in Texas just ruled today that two such gerrymandered districts are unconstitutional because there were clearly done along racial lines/to disadvantage black/brown voters.  There are districts where these votes literally do not matter.  If the dems can bring and win some key lawsuits in this regard the repubs will have to work to get the votes of more than just whites/and probably dems will have some work to do too.