(CNN) There was a time -- and it wasn't all that long ago -- where the worst thing you could call a Democratic politician with aspiring national ambitions was "liberal." Politicians ran from the label because they believed it connoted that they were out-of-touch, coastal elites -- not the sort of candidate who could win in a place like Ohio or Iowa or even Colorado.

Those days are over -- at least among Democrats, according to a new Gallup poll on partisan identification.

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While the percentage of people who self-identify as "liberal" has been increasing steadily from 17% in 1992 to 26% in 2018, the real change has been in how Democrats think of themselves. In 1994, 1 in 4 Democrats called themselves liberals -- the same number who referred to themselves as "conservative Democrats." The bulk of Democrats -- 48% -- said they were moderates. Today, for the first time in the history of Gallup asking the question, a clear majority (51%) of Democrats identify as liberal while 34% see themselves as moderates and and 13% regard themselves as conservatives.

As Gallup's Lydia Saad notes , the percentage of Democrats who identified as liberals rose, roughly, one percentage point a year from 2002 to 2014, but has picked up to two points a year since 2014.

What's interesting -- and telling -- is that a similar pattern hasn't played out among Republicans. Yes, more Republicans now identify as "conservative" today (73%) than did in 1994 (58%), but conservatives made up a majority in 1994 and still do two and a half decades later.

There are lots of potential reasons for these changes. As Saad notes, the growth of unaffiliated voters over the past decade could mean that "the two major parties may be increasingly comprised of the more hard-core adherents of each side's philosophy." Which makes sense. If moderates abandon the Democratic and Republican parties because they feel as though the two sides have become too ideological and partisan, then the people left in the parties are going to be -- wait for it! -- more ideological and partisan.

There has also been an aggressive movement within Democratic circles to reclaim the word "liberal" -- to make clear that they proudly wear that banner rather than past politicians like, say, Hillary and Bill Clinton, who prided themselves on their centrist approach, a not-so-subtle rejection of the "liberal" tag.

Case in point: An audience member named Rob Porter asked Hillary Clinton this question at a CNN debate in June 2007 in South Carolina : "Mrs. Clinton, how would you define the word 'liberal?' And would you use this word to describe yourself?"

Here's Clinton's full answer:

"You know, it is a word that originally meant that you were for freedom, that you were for the freedom to achieve, that you were willing to stand against big power and on behalf of the individual.

"Unfortunately, in the last 30, 40 years, it has been turned up on its head and it's been made to seem as though it is a word that describes big government, totally contrary to what its meaning was in the 19th and early 20th century.

"I prefer the word 'progressive,' which has a real American meaning, going back to the progressive era at the beginning of the 20th century.

"I consider myself a modern progressive, someone who believes strongly in individual rights and freedoms, who believes that we are better as a society when we're working together and when we find ways to help those who may not have all the advantages in life get the tools they need to lead a more productive life for themselves and their family.

"So I consider myself a proud modern American progressive, and I think that's the kind of philosophy and practice that we need to bring back to American politics."

Which, like, what? Clinton clearly just didn't want to say the world "liberal" because she was worried how Republicans might use it against her in a general election. That she never got to the general election in that campaign -- beaten by the more openly liberal Barack Obama -- was a telling moment in how the Democratic Party's relationship with the word was changing.

Compare Clinton's 2007 answer with what Bernie Sanders told The Guardian in the wake of the 2018 midterms. "Take a hard look at the [House Democrats] elected to Congress next year," Sanders said . "It's not just that many of them are women or people of color -- many of them are progressives who won their elections demanding Medicare for All, demanding raising the minimum wage to $15 an hour, and making public colleges and universities tuition free."

And it's not just a willingness to re-embrace the word "liberal." As the jockeying for the 2020 presidential race heats up, a number of potential contenders are crowding one another on the party's left via their support for longtime liberal dream policies including Medicare for All, free college and a $15 minimum wage. (Much touted liberal freshman Rep. Alexandria Ocasio-Cortez has proposed the possibility of taxing income over $10 million annually at 70% as a way to pay for the so-called "Green New Deal.")

Politicians are, by nature, a reactive species. With their livelihoods dependent on winning office (and votes), they tend to go where they believe those votes to be. The cavalcade of 2020 Democratic candidates sprinting to the left -- oftentimes seemingly trying to out-liberal each other -- is all the evidence you need (although the Gallup poll is useful too!) that the energy of the party is located in its liberal wing.

The broader question heading into 2020 is whether a candidate who runs for -- and wins -- the Democratic presidential nomination as an unrepentant liberal is someone who can win the White House. In the Gallup data, more people still identify as "conservative" (35%) than say they are "liberal" (26%). That gap has narrowed, yes, over the past decade. But in 2020, it's still very likely that more people who turn out to vote will see themselves as "conservatives" than "liberals."

Does that matter when you have a president as abnormal -- politically speaking -- as Donald Trump? We're going to find out in 665 days.