(CNN) Donald Trump just showed why even some Republicans question whether he has the temperament and the capacity to serve as President.

In an incredible performance at a raucous Arizona rally Tuesday, Trump rewrote the history of his response to violence in Charlottesville and reignited the culture wars.

Trump in effect identified himself as the main victim of the furor over the violence in Virginia, berating media coverage for a political crisis that refuses to abate over his rhetoric on race.

"They're trying to take away our culture. They're trying to take away our history," Trump said, blaming "weak, weak people" for allowing the removal of statues commemorating the Confederacy.

In defending his responses to the Charlottesville violence, Trump selectively omitted his reference to "many sides" or "both sides," comments he made that drew bipartisan condemnation for equating neo-Nazis with their counterprotesters.

Trump insisted at the start of his speech that all Americans must realize that they are on the same team, must show loyalty to their country, and that he wanted everyone to love one another.

But his performance was a fresh indication that he still feels far more comfortable, and perhaps motivated, to act as a political flamethrower who pulls at national divides than a President who wants to unite the nation.

Throwing gasoline onto political controversies, Trump threatened to shut down the government unless Congress funds his border wall and all but promised a pardon for Arizona Sheriff Joe Arpaio, who was convicted of contempt of court in a case related to racial profiling.

Taking on the establishment

He criticized Sen. John McCain, who is battling cancer, and turned on GOP senators he blames for his paltry legislative record. And he predicted talks to renegotiate NAFTA would fail.

It was a remarkable real-time glimpse into the inner frustrations of a sitting President, who apparently believes he is being persecuted by accurate media coverage of his conduct and can never get a break from critics.

"The only people giving a platform to these hate groups is the media itself and the fake news," he said.

Yet Trump's freewheeling speech, taking down establishment enemies one-by-one, was warmly received in his crowd, and will likely prove highly popular with the loyal core of voters who drove him to the GOP nomination and the White House. Those voters will lacerate media coverage of a speech that broke free of behavioral norms for the presidency, voter anger certain to be fueled by news outlets sympathetic to the President.

In effect, Trump's rhetoric on Tuesday amounted to an implicit warning about the wrath of a substantial sector of the Republican voting base should any party leaders seek to isolate or reject the President.

And it will create immediate new problems for Republicans on Capitol Hill agonizing about how to meet looming fiscal cliffs and budget deadlines and salvage their own agenda, not to mention the mid-term elections approaching next year.

The immediate context for the speech was a New York Times story that broke earlier in the day that said Senate Majority Leader Mitch McConnell had expressed doubt about whether Trump would be able to lead the Republican Party into the mid-term elections and beyond.

Last week's remarks by Republican Sen. Bob Corker, in which he questioned whether the President had the stability or the competence to be President, also took on new significance in the wake of Tuesday's fireworks.

The speech came a night after Trump had boosted the hopes of some Republicans by pulling off a sober, measured speech to the nation on his new approach to Afghanistan.

But his showing in Arizona made a mockery of some media assessments that at last the President had managed to measure up to conventional standards of presidential behavior. It was hardly the kind of performance that would cause other Republicans to conclude criticisms by McConnell and Corker were overblown.

Former Director of National Intelligence James Clapper, who served both Republican and Democratic presidents from John Kennedy to Barack Obama, said on CNN that he found the speech "downright scary and disturbing."

"I really question his ability to be, his fitness to be in this office and I also am beginning to wonder about his motivation for it. Maybe he is looking for a way out," Clapper said.

Mike Shields, a Republican political commentator, said that media critiques questioning Trump's mental state after the speech played into the President's hands.

"It's right to push back on that, it's right to hold him accountable, it's right to fact check him," Shields told CNN.

"But immediately after that, when the conversation shifts into he is insane, and he is unfit for office, and he has lost his mind and we are doing psychoanalysis on television of the President, you are doing his work for him. This is almost what he wants to see happen."

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Rallying the loyalists

Trump's boisterous showing appeared to be an attempt to fire up the political base that was the key to his election win last year.

Polls suggest his most loyal supporters still strongly support Trump, but also a worsening position for the President in the swing states that were key to his victory and signs that the strength of enthusiasm among GOP voters for his presidency is beginning to wane.

Early in his remarks, Trump reignited the controversy over his handling of the racially motivated protests in Charlottesville — fuming about the "sick" and "crooked" media coverage of his response to the episode, repeatedly and selectively reading from his remarks in the days after the tragic death of anti-white supremacist protester Heather Heyer.

While quoting from a printed copy of his remarks in the days after the protests, Trump accused the media, inaccurately, of ignoring his comments that "racism is evil" and condemnations of neo-Nazis and white supremacists.

He omitted his comment on the day of the protests blaming perpetrators on "many sides" and the equivalences that he again drew a week ago at Trump Tower between white supremacists and protestors.

"I hit 'em with neo-Nazi, I hit 'em with everything. KKK? We have KKK. I got 'em all," Trump complained.

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At times, Trump even seemed to be mocking his own White House team, amid reports that Chief of Staff John Kelly has been trying to rein in his wilder instincts.

Nor were Republican lawmakers immune to Trump's implicit criticism.

"One vote away, I will not mention any names," he said -- referring to the failed vote to repeal and replace Obamacare, a clear reference to McCain's vote.

Then, in a swipe at Arizona's other senator, Jeff Flake, another critic, Trump warned: "Nobody wants me to talk about him. Nobody knows who the hell he is. And now, we haven't mentioned any names, so now, everybody's happy."

Apart from the cultural and political rhetoric that will reverberate for days after the wild rally, Trump also appeared to make several policy interventions that will alarm US partners and could send economic shockwaves around the world.

"I think we'll probably end up terminating NAFTA at some point," Trump said, just after the start of talks on the vast trade pact with Canada and Mexico.

His threat to shutter the government over wall funding could have ramifications that stretch far beyond US shores, ahead of a deadline next month on raising the debt ceiling, without which the US government would default.

"Believe me, if we have to close down our government, we're building that wall," Trump said.

Outside the Phoenix Convention Center where the President spoke, police used gas canisters to disperse a crowd of anti-Trump protestors.

It was an eloquent metaphor for the political fury that has built through a broiling August, in which Trump has consciously widened political divisions in a bid to stabilize his reeling presidency.