For the last 8 years, Democrats have taken great satisfaction in referring to the GOP as a "small, regional, party." Despite big mid-term wins, Dems believed they'd crushed their opponents once and for all. Obama was popular, people were just going to love ObamaCare, and the country was moving left on social issues. Then Donald Trump happened.
Now, Democrats have a historically low number of office holders. As Ohio Representative Tim Ryan says in the clip below, Dems are "at the smallest number of Democratic members of our caucus since 1929," and currently boast "the smallest number of democratic office holders in the state and federal level since just after the civil war."