Editor’s Note: Julian Zelizer, a CNN political analyst, is a professor of history and public affairs at Princeton University and author of the book, “Burning Down the House: Newt Gingrich, the Fall of a Speaker, and the Rise of the New Republican Party.” Follow him on Twitter @julianzelizer. The views expressed in this commentary are his own. View more opinion at CNN.

CNN  — 

It looks like former President Donald Trump was willing to go even further than we knew in his war against leaks. According to the New York Times, prosecutors in the Justice Department obtained, via subpoena from Apple, information from the accounts of at least two members of the House Intelligence Committee–Representatives Adam Schiff of California and Eric Swalwell of California– and also looked into the metadata of their aides and family members (including at least one minor).

The administration was consumed with discovering the sources of leaks that the media was reporting on about contacts between associates of Trump and Russia. This story comes on top of recent revelations that this spring, the Justice Department notified reporters at CNN, The Washington Post and The New York Times that records had been seized in different investigations.

Trump’s Justice Department had pursued what appears to be a national security leak investigation that aimed to sweep up tens of thousands of a CNN reporter’s email logs, as well as phone records, from 2017.

These new reports are another reminder of the extreme exercise of presidential power that took place under Trump. Although it is easy to dismiss his four years in office as defined by a lot of loud Twitter noise and vicious political invective, this period also witnessed the aggressive deployment of presidential authority, sometimes conducted in secret, and in ways that threatened our fragile balance of power and the rights of American citizens.

The unfolding story about the Justice Department follows on many other well documented instances of abuse of power between 2017 and 2021.

During Donald Trump’s first impeachment the world witnessed the former president’s willingness to use foreign aid as leverage for obtaining “dirt” about a political opponent. Trump repeatedly used his Twitter bully pulpit to go after institutions—such as the media—and specific political opponents who were causing him trouble, even ultimately inciting a mob that attacked Congress and attempted to prevent the peaceful transfer of presidential power, based on fraudulent claims of a stolen election.

His invocation of national emergency powers to obtain funding for a border wall, despite bipartisan congressional opposition to spending money on this project, showed that he would let few things stand in his way. And in more familiar fashion, Trump turned to executive power to roll back initiatives meant to stop climate change, as well as workplace regulations and more that had been put into place by Democratic administrations.

How has this all happened? The former president was a product of two long-term trends that converged during his administration. The first has been the ongoing expansion of presidential power. Over the course of the twentieth century, the power, staff and regulatory authority accorded the president has vastly expanded.

During the Cold War and then in the “war against terror,” the growth of the national security apparatus handed the inhabitant of the Oval Office unprecedented resources with which to take action without congressional oversight. Even the elevation of the bully pulpit in the 20th century meant that the president, through his words, could affect public opinion in dramatic fashion.

The second trend was the triumph of smash-mouth partisanship within the GOP, creating a mentality at the highest levels of leadership that it was now permissible to do whatever was necessary to maintain power. This was a style that started to take hold with Congressman Newt Gingrich in the 1980s, accelerated with the Tea Party in the 2010s and culminated with the Trump presidency. It placed partisanship above the needs of governance or the health of political institutions. There was no longer a need for elected officials to balance all three responsibilities, according to this logic: every process and procedure could be weaponized when necessary.

If a president wanted to have his branch of government investigate members of another branch, for example, then so be it. As dramatic as this new story of the seizure of records from journalists and members of Congress story might be, it flows out of a basic dynamic that was well-established under the Trump presidency.

So far it seems that President Joe Biden, at least from what we know, is trying to pull back on his form of presidential power. He wants to be less Richard Nixon and more Jimmy Carter, someone who understands and respects the need to operate within boundaries, even if doing so comes at certain political costs.

But the bigger forces at work in this story all remain at play. Presidential power has reached levels that are not healthy for the nation. It is too easy for that power to be abused. In an age of intense political polarization, congressional oversight is unlikely. The partisanship-without-guardrails of former President Trump remains the guiding force for the GOP—as was evident when Senator Mitch McConnell decided to kill the creation of a bipartisan commission to investigate the Jan. 6 insurrection at the US Capitol.

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    And if Trump decides to run again in 2024, voters should understand that this is the kind of power they would be legitimizing for another four years. He might be anti-establishment and he might be the politician who says what he thinks, but he is also a president who can be fearsomely Nixonian.

    Too much presidential power is a dangerous thing. We have learned about this so many times over the decades. As in previous instances, the question remains—will American voters do anything about it, insisting to their representatives that the commander-in-chief be held accountable, or will they just wait for the abuse of power to happen again?