Although the Republican Party has grown more conservative in recent years, and the Democratic Party has grown more liberal, the Democrats rely far more on conservative voters than the GOP does on liberal voters. According to Pew, only 4 percent of Republicans identify as liberal, 27 percent as moderate, and 68 percent as conservative. By contrast, 46 percent of Democrats identify as liberal—a large increase from 2000, when it was only 28 percent, but far less than the percentage of Republicans who identify as conservatives. Moderates account for 37 percent of Democratic voters, and conservatives 15 percent.
That asymmetry means that Democrats are forced to appeal to groups that lean Republican in order to win. This sometimes leads to comically awkward pandering—think of former Vermont Governor Howard Dean declaring he wants to be president for the guy who has a Confederate Flag on his truck, or Hillary Clinton needling Barack Obama over his lack of support from “hard working voters, white voters.” When a Democrat with statewide or national ambitions does antagonize one of these conservative-leaning groups, whether it’s Obama describing Clinton primary voters as people who “cling to guns and religion,” or Clinton saying that half of Trump supporters are racist, it is a potentially campaign-ending gaffe.
Contrast that with a Republican senator like Ted Cruz, who accused his Democratic rival of trying to make Texas like California, “right down to tofu and silicon and dyed hair.” When Democrats trash Republican-leaning constituencies, it’s a political catastrophe. When Republicans trash Democratic-leaning constituencies, it’s Tuesday.