WASHINGTON – Just months after Donald Trump’s repeated campaign boasts about how smart he is, his White House and defenders now seem to be arguing exactly the opposite: that he shouldn’t be held accountable for his lapses because he doesn’t really understand what he is doing.

When Trump’s national security adviser, H.R. McMaster, defended the president’s sharing of sensitive intelligence information with Russian diplomats during an Oval Office visit last week, McMaster’s eventual explanation was that Trump could not have known the possible consequences of what he had done.

“The president wasn’t even aware, you know, where this information came from,” McMaster said.

The White House had to scramble after the Russians departed to let the CIA and the National Security Agency know what Trump had just said, presumably to inform Israel. The information in question reportedly came from Israeli intelligence ― and Russia is allied with Syria and Iran in the Syrian civil war, possibly risking the life of the Israeli agent who obtained the material.

“He doesn’t have a lot of experience with classified information,” said Republican consultant Matt Mackowiak. “There’s a little bit of a learning curve there.”

The White House did not respond to a HuffPost query for this article, but that “learning curve” argument has become common among Trump defenders, who argue that an “outsider” businessman should not be expected to understand the intricacies of government policy.

Trump critics, particularly those who are Republicans, say they find that rationale offensive, and see the latest episodes as proof that their warnings were correct all along.

“His erratic and dangerous behavior is just not sustainable,” said John Weaver, who managed Ohio Gov. John Kasich’s campaign for the GOP presidential nomination last year. “Six months ago, people were beating the hell out of us. … Not so much anymore.”

Kevin Lamarque / Reuters President Donald Trump speaks during the United States Coast Guard Academy Commencement Ceremony in New London, Connecticut U.S., May 17, 2017.

The latest examples of Trump’s lack of knowledge and lack of interest in acquiring it fit into a pattern stretching back to the start of his presidency, on issues both large and small.

In February, at an event commemorating Black History Month, Trump expounded on the virtues of Frederick Douglass, the Civil War-era abolitionist, as if he were an obscure figure, and in a manner that suggested Trump didn’t realize he has been long dead. “Frederick Douglass is an example of somebody who’s done an amazing job and is getting recognized more and more, I notice,” he said.

During the crafting of the House bill to partially repeal and replace former President Barack Obama’s Affordable Care Act, Trump explained that he only just learned that making one change in the health care system has multiple effects in other areas. “Nobody knew health care could be so complicated,” he said.

Similarly, after numerous claims that China could easily deal with North Korea’s nuclear militancy, Trump said that a conversation with Chinese President Xi Jinping brought him new insight into the centuries-long history of the two nations. “After listening for 10 minutes, I realized it’s not so easy,” Trump told The Wall Street Journal.

Trump could have informed himself on both topics as a private citizen, as a candidate running for the highest office in the country, or even as president ― by taking advantage of the expertise in his own Health and Human Services and State departments. Instead, he entered into discussions requiring background knowledge largely uninformed ― and then described his newfound information as if it were a major discovery.

(Even with a health care bill now passed out of the House, it is still not clear Trump understands how the system works. In a May 4 interview with The Economist, he described it this way: “Insurance is, you’re 20 years old, you just graduated from college, and you start paying $15 a month for the rest of your life and by the time you’re 70, and you really need it, you’re still paying the same amount and that’s really insurance” ― an explanation that does not at all reflect how health insurance actually works in this country.)

All of this has presented a challenge for White House staffers, who each day try to brief a president who is not terribly interested in being briefed and loses attention quickly.

HuffPost reported not long after he took office that Trump did not like briefing books, and preferred memos no longer than a single page that used bullet points, and contained no more than nine bullet points on that page.

And Reuters reported Wednesday that National Security Council aides prepping Trump for his upcoming foreign trip, the first of his tenure, have made sure to include his name frequently in the briefing material because “he keeps reading if he’s mentioned.”

Trump’s lack of knowledge about national and world affairs was abundantly clear during the 18-month presidential campaign, when he frequently and repeatedly made incorrect statements on topics including illegal immigration, crime rates, trade policy and terrorism.

Trump himself, though, sold himself as a man of great intellect, often pointing out that his uncle had taught at the Massachusetts Institute of Technology. “Good genes, very good genes. Okay? Very smart,” he said at a South Carolina rally.

Many of his supporters appeared ready to accept Trump’s version of himself, often offering the explanation that as a successful businessman, he was obviously smart enough to learn what he needed to become a successful president.

In reality, Trump’s business record has been mixed, at best. He took over his father’s real estate company at the age of 28 in 1974. Its value in today’s dollars was close to $1 billion. Despite that start, Trump underperformed both the stock market and, even more dramatically, the real estate market over the decades, leaving him with a net worth billions lower than if he had simply liquidated his assets and invested in those funds.

He ran his family business much as he runs the White House now ― based on whims with little research. This resulted in his ownership of a money-losing airline, and put him on the brink of personal bankruptcy after his purchases of several Atlantic City casinos.

Trump’s main business in recent years has been licensing his name to hotel and condominium buildings that he does not own ― thanks to the success of his TV show, “The Apprentice,” in which he played a savvy and decisive businessman.

“He’s clearly a great salesman,” Mackowiak said. “He’s developed a brand a long time. And a lot of voters found that appealing.”

Republican National Committee members and donors also bought into the Trump “brand” last year, after it became clear that Trump, and not one of the favored “establishment” candidates, would win the GOP nomination. Only now, with Trump’s ignorance manifesting itself almost daily, are some of them coming to appreciate what happened.

“People in the process don’t understand how little people outside the process know about either the process or the substance of the issues in government,” said a senior RNC member on the condition of anonymity. “I think the assumption is that subject knowledge can be handled by appointees. Get good people with knowledge and they will fill in the gaps. The problem comes when you don’t have knowledge and try to do it yourself, instead of deferring to those with knowledge.”

Other Republicans see a much less charitable explanation for their party’s continued support for Trump: an expectation that Trump would be so malleable and so uninterested in policy details that he would sign whatever legislation they put on his desk.

“They would let Donald Trump kill and eat their children if they can get their business tax cut,” said Rick Wilson, a Florida consultant who supported Sen. Marco Rubio (R-Fla.) in the primary, and has remained a vocal Trump critic all along.

Wilson said some in his party may have seen Trump’s behavior as showmanship ― an act to win the presidency. The events and revelations of recent days, Wilson said, should help clear that up.

“The mania and lunacy wasn’t an act,” he said. “It’s a true, honest-to-God political train wreck.”