The idea of the working class is often employed in political dialogue, yet its definitions are fraught. Working class has been identified with occupation, education, income or self-identification. We argue that economic precarity is an important aspect of working class status that is often not directly captured by other measures. We find that when asked, voters often suggest precarity as a defining characteristic of working class in the United States. Next, we show that high levels of economic precarity predict self-identifying as liberal, a Democrat, and disapproving of President Donald Trump even while controlling for an individual's race, gender, age, education and income. We also find that precarity has a persistent effect for white and non-white voters. Overall, we show that by ignoring precarity as an aspect of the working class, researchers are missing important aspects of how working class status is conceived in the United States.