Well, well, isn't this interesting. NBC:

American politics is full of second acts, but the biggest rehabilitation in 2019 may be around the word “liberal.” For years, even Democrats shied away from the moniker. But new data show that L-word has emerged from its exile, and is being embraced again by those who once shunned it.

This week Gallup released data showing that, for the first time since 1994, more than half of Democrats, 51 percent, identified their political views as “liberal.”

It's likely the Medicare-for-All healthcare debate, along with growing acceptance for gay marriage and legal pot, has a lot to do with this phenomenon.

...the Democratic Party, and the country as a whole, have moved leftward, even in the age of President Donald Trump. One big result: Issues that were once deemed too liberal for the mainstream, even among Democrats — Medicare and/or college for all, universal employment, abolishing ICE — may play a big role in the 2020 campaign.