Donald Trump’s behavior in the aftermath of the largest mass shooting in U.S. history has erased all doubts, if there were any left, that he is determined to leave all the norms of American politics in the dust.

The country had barely woken up to the news from Orlando Sunday, and other leaders were confining their comments to condolences, when Trump took a bow on Twitter for “being right on radical Islamic terrorism.”

An hour later, the presumptive Republican nominee tweeted that President Obama should “resign in disgrace” if he is unwilling to label the carnage “radical Islamic terrorism.”

By Monday morning, Trump was on Fox News, appearing to question the commander-in-chief’s loyalties, saying Obama “is not tough, not smart, or he’s got something else in mind.”

This is Trumpism.

After the deadly shooting in an Orlando nightclub on June 12, some in politics pushed for stricter gun control while others asked for prayers. GOP presidential candidate Donald Trump ignited controversy with his tweets. (Jenny Starrs/The Washington Post)

When the celebrity real estate mogul declared his candidacy for president, a year ago this week, his declarations and discredited theories, conveyed in a seeming constant stream of tweets and media interviews, still had the capacity to shock. His characterization of some Mexican immigrants as murderers and rapists caused a sensation.

But now the kinds of outbursts that might have been disqualifying for any other politician, or at any other time, almost seem like standard fare — which is itself a testament to how Trump has reoriented the axis of politics and discourse. And everyone else is forced to adjust, from lawmakers in Trump’s own party to his likely Democratic opponent, Hillary Clinton.

“We haven’t ever seen anybody have this sort of dialogue with the electorate,” said GOP pollster David Winston.

In a tacit acknowledgement of the Trump effect, Clinton on Monday used the term “radical Islam,” which she had previously rejected. “She isn’t going to let us be distracted with semantic games,” a Clinton aide explained.

Trumpism is not defined by any set of policies, or an ideology. It is not handcuffed to coherence or consistency, except in its disregard for what its adherents deem to be political correctness.

Trumpism is a personality- fueled movement that has proven, against the smart money’s predictions, to be in tune with the frustrations of a significant slice of the electorate.

Having drawn record numbers of voters to the polls during a Republican primary in which he vanquished a slew of conventional candidates, Trump is betting that his brand of politics will be just as compelling in a general election against the ultimate Democratic establishment figure.

“He’s not playing for a team. It’s just him making the calls,” said Robert Jeffress, a Dallas pastor who has grown close to Trump during the campaign. “He’s somebody who thinks it’s worth asking questions about whatever is going on, and not worrying about whether he should keep his curiosity to himself.”

Trumpism resonates in an anxious era, and with a segment of voters who have given up on Washington.

“People out there are worried about their jobs and their security and about allowing all of these people to come to America,” said Rep. Lou Barletta (R-Pa.), a Trump supporter and hard-line voice on immigration policy. “They don’t want talking points as a solution to their frustration.”

They also believe that Trump cannot be pushed around by a system to which he is not beholden.

“Trump is someone who comes in and hasn’t been in the bubble of Washington,” Barletta said. “He’s not part of the system that people see as corrupted, so when he goes with his gut, he’s trusted.”

Although it is not entirely like anything the country has seen before, Trumpism has echoes in the kind of populism associated with earlier figures such as Democrat Huey Long, the Depression-era governor of Louisiana.

William Galston, senior fellow at the Brookings Institution who has advised Democratic presidential campaigns, ticked off the characteristics: “intensely nativistic, ethno-centric, exclusionary, angry, fearful.”

“At the bottom of the barrel is the rottenest thing of all, which is conspiratorial thinking, which is guaranteed to pollute every single issue and every single argument,” Galston said. “Conspiratorial thinking is the cesspool of conservative populism. It has analogs on the left, but it is a distinctive phenomenon.”

Trump, who became a hero to some Obama haters when he led the discredited movement questioning whether the president had been born in this country, routinely passes along unfounded theories and accusations about his adversaries on social media, shrugging it off when their veracity is questioned.

Those around him amplify those darker themes of Trumpism.

Roger Stone, who last year parted ways with Trump’s campaign but remains close to the candidate, on Monday accused top Clinton aide Huma Abedin, a Muslim, of being a “Saudi spy” or a “terrorist agent.”

In an article on Breitbart’s website, Stone wrote of his theories about Abedin: “It’s time America got some answers.”

Former Mitt Romney adviser Kevin Madden said Trump’s tactics are “a problem for the party in how they force other Republicans down ballot to have to either defend, agree with or condemn what he said.”

At the same time, Trump can sound open and inclusive on some issues. He blends a modern Manhattan sensibility with his old-school Queens demeanor.

In a speech on Monday, he doubled down on his controversial call for a temporary ban on all Muslims entering the United States, but he also made a full-throated denunciation of bigotry against gays, lesbians and transgender people.

The attack on a gay nightclub was “a strike at the heart and soul of who we are as a nation. It’s an assault on the ability of free people to live their lives, love who they want, and express their identity,” Trump said.

Part of what propels him is his comfort level with 21st-century communication, as evidenced by his constant presence on Twitter. Clinton has begun to borrow some of this techniques — for instance, frequently phoning into television news shows lately.

Kellyanne Conway, a veteran GOP strategist, said there are limits to how far the force of Trump’s personality can carry him as the general-election campaign unfolds.

While Trump can overwhelm a news cycle, she added, fundamentals on the ground and air still matter.

Clinton has a massive advantage in organization and money, Conway said. “He doesn’t need to meet her dollar for dollar, employee for employee, but the gulf shouldn’t be that steep. Super PACs and others are going to have to help him to sustain what he has, which I think they will.”

What the former star of NBC’s “The Apprentice” has done in some ways, Conway said, is to introduce the reality-show zeitgeist to politics.

“He knows that the culture is everything, and to attract people, you need to be in the culture. He has tracked ratings and his audiences for years and understands how public opinion works,” Conway said. “He studies the polls, and his crowds are his focus groups.”

And in the end, the only instincts that Donald Trump truly trusts are his own.

Abby Phillip contributed to this report.