As a candidate, Donald Trump vowed to dismantle some of President Obama's key achievements. Washington Post White House reporter David Nakamura breaks down what the Obama administration is worried about going forward. (Sarah Parnass/The Washington Post)

For months, President Obama has been worrying both publicly and privately about the growing threats to American democracy. They included a broken and dysfunctional Republican Party, a balkanized media, and an angry and suspicious electorate.

At the top of Obama’s list — the physical embodiment of those gathering and potentially existential threats — was Donald Trump, from whom Obama sat inches away in the Oval Office on Thursday.

The president had mocked Trump as a temperamentally unstable reality-TV star who regularly demeans women and minorities and was unfit for and unworthy of the country’s highest office. Following their first-ever meeting, Obama emphasized the need “to now come together, work together, to deal with the many challenges that we face.”

Trump’s win raises difficult questions for Obama that he and his top advisers have only just begun to confront: What role, if any, did Obama, his policies and his approach to the presidency play in Trump winning the White House? For more than a decade, Obama has forged a national political identity around the uplifting idea that Americans share a core set of liberal, democratic values that run deeper than the country’s racial, class and ideological divisions. Why did those divisions only seem to deepen over the course of Obama’s two terms in office?

“This has been a deeply dispiriting election year,” Obama recently told donors at a Democratic fundraising dinner in Ohio. “Sometimes you wonder, how did we get to the point where we have such rancor?”

Intentionally or not, some of the president’s actions probably contributed to that rancor. He was insulated by a White House bubble and a staff with fewer ties to those parts of the country that were most alienated. His executive actions, essential to advancing his agenda in an era of gridlock, inflamed an increasingly partisan electorate. Meanwhile, a micro-targeted media strategy sometimes took precedence over speaking to the entire country.

Inside the West Wing, there were tears, sadness and a general feeling of disbelief that even though Obama’s approval rating now stands at 56 percent, a significant number of his supporters backed Trump’s sometimes dark, nativist and anti-immigrant vision for the country. “I don’t have an explanation for that, to put it bluntly,” White House press secretary Josh Earnest said.

Senior White House aides rejected the idea that Obama bore responsibility for Trump’s victory or that the election was a referendum on the Obama presidency. “An election is a comparison between two people, and two candidates on the ballot,” White House communications director Jennifer Psaki said in an interview last week.

But White House officials, including Obama, who had described a Trump victory as a near-impossibility, were shocked by the depth of anger and fear that swept Trump to the White House.

Throughout his second term, Obama spoke only fleetingly of the economic pain in the country caused by globalization, demographic changes and technological advances. His second-term agenda has been dominated by immigration initiatives and a far-reaching trade deal with Asia.

Often, he seemed to question the depth of the anger and division in the country, noting that he was twice elected to the White House. “There are always going to be folks who are frustrated,” Obama told NPR’s “Morning Edition” in December as Trump was gathering support. “Some of them may not like my policies; some of them may just not like how I walk or my big ears.”

Speaking at the White House, Nov. 9, President Obama vowed to work towards a peaceful transition of power to President-elect Donald Trump and encouraged young people not to become cynical. Here are key moments from that speech, in three minutes. (White House)

In rare moments, he suggested that his race, name and upbringing may have helped inflame conspiracy theories about him in some segments of the Republican Party. “I may represent change that worries them,” he told NPR.

Obama didn’t completely ignore the struggles of rural, white Americans: His administration proposed spending more than $1 billion to deal with the opioid and heroin crisis that has ravaged rural America and is contributing to an unprecedented rise in mortality rates among working-class white men and women. His first-term efforts to save the automobile industry benefited blue-collar workers, as did the push to expand Medicaid, which was blocked by some Republican governors and legislators.

But on the campaign trail, Obama sometimes seemed to have trouble connecting with the economic anxieties in rural parts of the country, referring to them fleetingly in his speech at the Democratic National Convention this summer as “pockets of America that never recovered from factory closures.” He focused instead on the 15 million jobs created during his second term and the country’s falling unemployment rate.

Senior White House officials in January described ambitious plans to have the president speak more directly to Americans who disagreed with him. But those efforts were often sidetracked by higher priorities, such as police shootings and protests this summer.

By early fall, Obama had shifted his focus to mobilizing young and minority voters, who were a key part of his coalition and had been slow to warm to a Hillary Clinton presidency. Obama attacked Trump as ignorant, vain and coldhearted. His mocking of the billionaire as better suited to “The Bachelorette” or “Survivor” than the Oval Office sometimes made it seem as if he were also mocking Trump’s supporters.

Even Obama seemed to concede the failure of his efforts to ease the country’s growing anger and divisions. He rejected the idea that his policies alienated the white working class. “The truth is that every policy I’ve put forward would make a huge difference with the white working class and the black working class and the Latino working class,” Obama told HBO’s Bill Maher a few days before Trump’s victory.

But Obama conceded his broader failure in an era of “800 television stations” and thousands more websites to convince these voters that he understood their frustrations and that his policies were making a difference. “In this new age, what is the equivalent of getting into people’s living rooms and having a conversation?” Obama asked. “I have not always been able to do it as successfully here in the White House, partly because of this bubble that’s created around me.”

In some instances, Obama’s strategy for dealing with the polarization in the country may have made the problem worse. To drum up support for its policies, the Obama administration often sought out new media venues to mobilize small, loyal audiences. After his State of the Union address, for example, Obama sat for interviews with enthusiastic and often fawning YouTube stars to talk about his agenda for 2016, the tax on tampons and why he preferred rapper Kendrick Lamar to Drake.

To overcome a gridlocked Congress, he relied heavily on executive orders and actions to spur progress on immigration, climate change and gun control. The surge of high-profile executive moves boosted Obama’s popularity but angered his opponents.

“It was all edicts — fiat government,” said Mark Krikorian, executive director of the Center for Immigration Studies, which advocates for lower immigration levels.

Despite Trump’s win, Obama will leave the White House with some of the highest approval ratings of his presidency. First lady Michelle Obama and Vice President Biden have garnered even more support in polls.

The president’s surging popularity convinced his top aides that the anger in the country was not directed at him and his policies but at an implacable Republican Party that had prioritized obstruction and gridlock over reason and compromise. Today, even Obama’s staunchest backers concede that the theory might be wrong.

“It would be a mistake if the Democratic Party didn’t use this as a sobering moment of reflection on whether or not we are connecting, or if we’re trying to connect in an outdated manner,” said a senior administration official who spoke on the condition of anonymity to discuss the election frankly. “That’s not a matter of tactics . . . that’s more whether we’re hearing and listening to what people are experiencing in the country.”

The president in private conversations with his staff has described the next 70 days, leading up to Trump’s inauguration, as a key test of his presidency. One of his main jobs, alongside Trump, will be to start healing the nation.

“He recognizes it is going to [take] more than one speech in the Rose Garden,” the senior administration official said.

In 2004, Obama burst onto the national political scene with an electrifying promise to unite the country. “There’s not a black America and white America and Latino America and Asian America; there’s the United States of America,” he said.

The bigger question, perhaps the central question of Obama’s 12 years on the national stage, is whether the country has become too big, too diverse and too unruly to be guided by one voice. This was the question Obama seemed to be asking this summer at a memorial service for five slain Dallas officers.

“Can we do this? Can we find the character, as Americans, to open our hearts to each other?” he asked. “I don’t know. I confess that sometimes I, too, experience doubt.”

David Nakamura contributed to this report.