Not only that, but the majority party as well.
While both Dems & Repubs have been losing members, the GOP has been losing them at a far greater rate. If it wasn't for gerrymandering, they'd be functionally extinct in most of the US, other than in some backwater rural counties. Republican Presidents have won the popular vote only once in the last three decades (2004), hence why they're so adamant on not getting rid of the ridiculous Electoral College.