Julian Zelizer is a history and public affairs professor at Princeton University, editor of " The Presidency of Barack Obama: A First Historical Assessment " and co-host of the "Politics & Polls" podcast. Follow him on Twitter: @julianzelizer . The opinions expressed in this commentary are those of the author. View more opinion articles on CNN.

(CNN) In a speech at a Democratic fundraiser in Iowa, attorney Michael Avenatti, who is toying with a potential presidential run in 2020, made a provocative statement. He rejected the famous advice of former first lady Michelle Obama who said , "When they go low, we go high."

Avenatti, who entered into the political spotlight through his defense of Stephanie Clifford, the adult film actress known as Stormy Daniels, told an excited crowd in northern Iowa that "we must be a party that fights fire with fire. When they go low, I say hit back harder."

Avenatti is right. With two critical elections on the horizon -- 2018 and 2020 -- Democrats need to wake up from their civil slumber and understand that turning back the modern Republican Party, with President Donald Trump as its Batman and the Freedom Caucus as its Robin, will necessitate engaging directly in the hard-hitting, media-centered, political combat zone within which elections are now determined.

Despite the weaknesses that were exposed about the GOP in Tuesday's special elections, the Democratic Party should certainly not make the same mistake it did in 2016, believing that the nation would inevitably reject the kind of politics that Trump represents.

While Barack Obama did find a way to make civil electoral politics work in 2008, this is not a recipe that is going to work today against a Republican Party consistently willing to go to any length to win.

A year ago, after the "Unite the Right" rally in Charlottesville, Virginia, in which white nationalists marched, shouting racist chants -- the same rally that resulted in the death of Heather Heyer -- the President of the United States refused to come down hard against the white nationalists. As protests were expected in Charlottesville on the anniversary of the rally, however, Trump took to Twitter on Saturday to "condemn all types of racism and acts of violence."

Democrats need to accept the nature of the political fight they face. To be sure, Democrats need to find a set of principles that inspire and excite their votes. But just as urgent is the need to find candidates who understand what has become of national politics and now are willing to go after their opponents with the same ferocity and ruthlessness as many of their Republican opponents.

Without question, whoever the Democratic nominee is in 2020, Trump will go after him or her with hammer and tong, aiming to destroy their reputation, credibility and viability with a barrage of insults and smears. The Republicans will find media figures such as Fox host Laura Ingraham who are even willing to spread the rhetoric of white nationalism . (On Thursday, Ingraham denied that comments she had made on air lamenting "massive demographic changes" were in support of white nationalism.)

In a recent episode of CNN's " The 2000s ," viewers were reminded about the costs of always taking the high road. The show examined the contested presidential election of 2000, where Republicans, guided by James Baker, launched an all-out political campaign to win the public relations war over the presidential election vote recount, while Democrats, headed by Warren Christopher, tried to handle the controversy in more civil fashion, treating it as a purely legal battle. The outcome: Democrats lost and George W. Bush became President.

Some of the most successful Democratic candidates have been willing to get their hands dirty in the quest for partisan victory. Most famously, in 1964 President Lyndon Johnson obliterated Barry Goldwater with a ferocious campaign that painted the senator from Arizona as an extreme and unstable right-wing Republican who was irresponsible enough to allow the social safety net to be blown up -- and the entire world with nuclear weapons as well.

The famous " Daisy " ad depicted a small girl counting the petals that she picks off a daisy. She counts to 10, then viewers hear a male voice count down from 10 to one. The camera zooms in on one of her eyes, then a nuclear explosion fills the screen and Johnson's voice comes on, "These are the stakes: to make a world in which all of God's children can live or go into the dark. We must either love each other, or we must die." Johnson defeated Goldwater in a massive landslide victory, and Democrats won huge majorities in the House and Senate.

In 1992 Bill Clinton did the same. Sick and tired of the losing Democratic candidates who treated Ronald Reagan and George H.W. Bush with kid gloves in 1984 and 1988, to the detriment of the party, Clinton and his adviser James Carville established a "war room," famously captured in a brilliant documentary of the same name by Chris Hegedus and D.A. Pennebaker.

Carville and his team understood that defeating the elder Bush would require a campaign that hit back as hard as Republican consultant Lee Atwater had done to Democrats back in 1988. The Clinton campaign responded to every single accusation that Bush's campaign made. They did so quickly and they did so aggressively. "The War Room" also looked for every opening that emerged to paint the opponent as a dishonest, out-of-touch and right-wing Republican in the clothes of a centrist.

Democrats will need this mentality again -- the one that Avenatti is suggesting -- if they are going to make the blue wave happen in November and if they are going to recapture the White House in 2020. This is not the time to insist on civility, nor is it the time to insist on claiming the high ground in a political world where it has disappeared.

Democratic candidates will need to be direct about the kind of world that many Republicans are peddling, the risks and dangers that Trump has subjected the nation to, and they will need to do so through a strategy aimed at drumming up their own support and conveying their message in a world shaped by Twitter and cable television.

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Otherwise, Democrats might very well go high, but they will do so as they watch the Republicans retain control over the institutions of government.