Editor’s Note: Julian Zelizer, a CNN political analyst, is a professor of history and public affairs at Princeton University and author of the forthcoming 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  — 

Senate Majority Leader Mitch McConnell made a very bold statement on Thursday during an interview with Sean Hannity on Fox News. Although Senate Republicans are supposed to be part of a jury hearing the evidence from the House managers, the majority leader bluntly stated that he would be in “total coordination” with the White House on the trial strategy.

Julian Zelizer

“There will be no difference between the President’s position and our position as to how to handle this, to the extent that we can,” McConnell said.

The statement was extremely revealing. Instead of giving the impeachment articles a fair hearing and a serious trial, the Senate majority leader is just going to give Trump total impunity.

Some commentators, including Carl Hulse of the New York Times, have argued that impeachment could be normalized as just another tool of partisan conflict going forward. Instead of speculating how partisanship will play out in the future, we should turn our focus instead to the way partisanship has paved the way for President Trump and benefited him in this terrible saga.

Presidents are not kings. They are given the leeway to act in an imperial fashion when Congress forgoes its duty to oversee the executive branch or in this case, when one party is willing to overlook charges of the misuse and abuse of presidential power.

President Trump may have felt free to wield his presidential power in the way that he did because congressional Republicans have protected him from day one. Despite many moments of private grumbling, Republicans have consistently stood by the President. Regardless of whether their loyalty stems from the fear of losing their jobs or a genuine affinity with the President, Trump has been able to count on his party to save him.

Each time that Trump has found himself in political hot water, congressional Republicans have run to his defense. This kind of loyalty was on display following the shocking revelations of the Mueller report, when the GOP turned a blind eye to damaging findings about the way he conducted his campaign as well as evidence of seeking to obstruct justice. But when the report arrived in Congress, Republicans didn’t flinch. They blasted the findings as irrelevant and manufactured their own spin about what this team of investigators said.

After the Republicans’ defense, the President may have felt free to solicit foreign election interference by pressuring the Ukrainian president to launch an investigation into his political opponent. Even though some members of Congress initially claimed that the July 25 phone call was “troubling,” the Judiciary Committee hearings made clear that, ultimately, the Republicans would fall in line.

House Judiciary Republicans did not really debate the substance of what happened nor did they engage in genuine deliberation about how we need to restrain presidents.

With Republicans in control of the Senate, the President can rest easy when it comes to the next stage of the impeachment proceedings. Republicans can either move to dismiss the case or turn the trial into a circus to trot out stories and witnesses in an effort to damage the Democrats.

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    Congressional Republicans have laid the groundwork for the President’s behavior. We have reached this moment not because partisan polarization has driven Democrats to impeach Trump. We are here because one party — the GOP — was so hell-bent on preserving political power that it allowed the commander-in-chief’s abusive behavior. And it is this sort of partisan protection that allows the President to push the boundaries of what is considered permissible in our democratic system.

    The question before us right now is not where polarization will bring us in the next few years. Instead we should ask what will happen now that Republicans have chosen this path of all-out partisanship, which erodes our democratic institutions by greatly weakening the systems of checks and balances.