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 “Abraham Joshua Heschel: A life of Radical Amazement.” Follow him on Twitter @julianzelizer. The views expressed in this commentary are his own. View more opinion on CNN.

CNN  — 

Republican Texas Sen. Ted Cruz got himself into some trouble with one of the party bosses at Fox News this week.

The problem began on Wednesday, when, in a US Senate hearing, Cruz said that the nation was approaching “an anniversary of a violent terrorist attack on the Capitol where we saw the men and women of law enforcement demonstrate incredible courage, incredible bravery, risk their lives to defend the men and women who service in this Capitol.” The choice of using the word “terrorist” echoed remarks that he’d made in the past – including on January 7, 2021, a day after the attack.

Tucker Carlson, the Fox News host who has gone out of his way to downplay and distort the terrible events of that day, was less than pleased. He reprimanded Cruz on Thursday night – and, in doing so, sent a clear message: in today’s Republican Party, he – not Cruz – has all the power.

Carlson started his segment by accusing Cruz of lying for referring to January 6 as a “violent terrorist attack.” Cruz didn’t take long to backtrack, saying to Carlson in an interview on Fox News: “The way I phrased things yesterday – it was sloppy, and it was, frankly, dumb.”

When Carlson refused to accept the apology, a groveling Cruz said he was just talking about a “limited number” of people who assaulted police officers – not the “thousands of peaceful protesters” supporting former President Donald Trump.

But Carlson was having none of it. “I guess I just don’t believe you,” he remarked. The Fox News host then said that Cruz, a former trial lawyer, has always chosen words carefully and was providing fodder to Trump’s critics by branding his supporters in such a negative light.

Of course, the rumble made for good television – a prominent right-wing pundit taking on a prominent right-wing legislator, who had himself been a leading voice in the campaign to challenge the legitimacy of the election. In many ways, the moment had the feel of a revolution swallowing one of its own. The politician who has stood right by the former President and the party’s assault on the electoral system was now being accused of helping the opposition.

But the interaction was also an important reminder of the immense power that the conservative media ecosystem holds on the party – and more specifically that Fox News maintains in shaping the tone and the agenda of the GOP. When any Republican legislator dares to step out of line, the network’s hosts are ready to push back and make clear there is a cost to be paid for taking even the slightest political detour.

And their ire isn’t limited to Cruz. When Illinois Rep. Adam Kinzinger criticized Trump for challenging the 2020 presidential election results, Fox News host Mark Levin tweeted that he was “a devious and reckless” politician. In recent months, those sorts of attacks have only intensified against Kinzinger, who has become a prominent member of the House select committee investigating the events around January 6.

Beyond exemplifying the power of right-wing media, Carlson’s exchange with Cruz also provides clear evidence that the radicalized state of the GOP cannot all be attributed to Trump. Though there is an inclination among many Democrats – including President Joe Biden – to focus their criticism on Trump, the reality is far more complex.

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    Trump’s emergence on the political scene is a consequence of the Republican Party’s sharp turn rightward – both in terms of its policies and tactics over the last several decades. From the smash-mouth partisanship of legislators like Newt Gingrich in the 1990s, to the growth of conservative media in recent years, Republican politics helped set the stage for Trumpism before they became one and the same.

    And if any Republican politician feels that there is any leeway to deviate from the party line now that Trump is no longer in office, he or she should re-watch the Carlson-Cruz segment. The forces of an extremist GOP remain as strong as ever – and regardless of whether Trump decides to run again in 2024, the kind of radical Republicanism that he has championed will continue to endure.

    Among many others, we can thank Tucker Carlson for that.