Democracy in the United States is in decline. The current work examines to what degree U.S. Americans perceive this decline in the U.S., and how partisanship may shape those perceptions over time. Using cross-sectional archival data spanning three U.S. presidential administrations (Study 1), we find that perceived levels of democracy by U.S. Americans on both sides of the political spectrum were not attuned to objective democracy indices but instead followed a partisan gap where election winners perceived higher levels of democracy than election losers. Using a longitudinal quasi-experiment tracking the 2020 presidential election (Study 2), we find that the effect of partisanship on perceived levels of democracy kicked in right after the announcement of the election winner but was the strongest after the official inauguration. Moreover, Trump supporters showed heterogeneous responses to the Capitol attack, which highlights the possibility of bipartisan willingness to defend democracy after salient attacks on democratic principles. We discuss the implications of the effect of partisanship on perceptions of democracy.