Democratic presidential candidate Hillary Clinton and Sen. Bernie Sanders (I-Vt.). (Melina Mara/The Washington Post)

Doug Sosnik, a Democratic political strategist, was a senior adviser to President Bill Clinton from 1994 to 2000.

There's been lots of talk about a supposed civil war brewing within the Democratic Party, as its centrist and progressive wings vie for power. But at least as a matter of presidential politics, this talk isn't premature — it's too late. The war may not have been won but the eventual victor is clear: By the end of the 2020 presidential primaries, an increasingly liberal grass-roots activist base is likely to have gained full control of the party.

The party that nominated Barack Obama to the presidency almost a decade ago had moved considerably to the left by the end of his second term. Hillary Clinton was barely able to withstand these changes in her campaign against Bernie Sanders. She ultimately secured the nomination by harnessing the remnants of the decaying Democratic political apparatus and racking up overwhelming support from the appointed superdelegates.

This transformation has been building since the beginning of the past decade, fueled by Bush v. Gore, George W. Bush's subsequent decision to go to war in Iraq and growing income inequality exacerbated by the economic crisis. The Trump presidency has only further energized the liberal base.

It is difficult to overstate the depth and breadth of the move to the left on social and economic policies among Democrats since Bill Clinton’s presidency. The Pew Values Survey released last month found that the percentage of Democrats and Democratic leaners who express liberal or mostly liberal political values exploded from 30 percent in 1994 to 73 percent in 2017.

The research found that 84 percent of Democrats think immigration is a good thing for our country — a 52-point increase since 1994. And 64 percent now believe that racial discrimination is the main reason that many black people cannot get ahead — a 36-point increase in the past seven years. A June 2017 Pew poll found that a majority of Democrats support single-payer health insurance, a 19-point increase in just the past three years.

Other factors will continue to push the party leftward, including demographic trends, the growing geographic concentration of like-minded voters and changes in the Democratic Party’s nomination process.

The demographic changes are generational as well as racial. In 2018, for the first time, millennials will surpass baby boomers as the largest cohort eligible to vote. The most recent U.S. Census data show that more than 44 percent of millennials in the country are minorities and that more minorities are born each year than non-Hispanic whites. These millennials are the most anti-Republican and anti-Trump of any voter group due in large part to their views on social issues. In addition to embracing a progressive agenda on virtually every social issue, millennials are particularly energized by issues such as energy and the environment, which they prioritize at the voting booth.

At the same time this generational shift unfolds, Democrats are increasingly self-selecting where they live and whom they choose to live near. President Trump carried 84 percent of U.S. counties, but the remaining areas, located largely on the coasts as well as urban areas in the middle of the country, voted overwhelmingly for Clinton. As much of the country moved to the right to elect Trump, the geographic areas that voted for Clinton moved further to the left. This shift is leading to the election of more progressive political leaders in the Democratic Party as these strongholds have become the political frontlines in the war against Trump.

The likely changes in the 2020 Democratic primary process will also push the party further to the left. The revelations in former party chair Donna Brazile's new book will put pressure on the Democratic National Committee's leadership to make the nomination process more transparent, while reducing the influence of the establishment in the primaries. Perhaps even more significantly, moving the California primary up to March 3 will push the candidates to take increasingly progressive positions on issues that appeal to this rich bounty of voters.

Republicans, of course, are experiencing their own internecine battles. Yet for all the implications of the Trumpification of the Republican Party, the impact for Democrats could be even more enduring. Unlike the Trump takeover, which was rooted more on blowing up the system than on any deeply held philosophical views, the changes in the Democratic Party are grounded in a firm set of ideological beliefs driven at the grass-roots level.

This transformation is not without risks for the party. According to 2016 Gallup polling, while 25 percent of adults now consider themselves liberal, an eight-point increase since 1992, we remain a center-right country, with 70 percent of Americans self-identifying as either moderate or conservative.

The central challenge for Democrats in taking back the White House will hinge on the party’s ability to persuade a majority of Americans to support a more progressive agenda going forward. While the country is moving in that direction, it is not there yet.