Just six months after telling Matt Lauer he couldn't imagine Donald Trump giving a State of the Union address — except in a "Saturday Night Live" skit — President Barack Obama now says "anything is possible" in November.

"It is the nature of democracy that until those votes are cast and the American people have their say, we don't know," Obama explained in an exclusive interview with TODAY's Savannah Guthrie.

During that previous interview — conducted on the eve of his final State of the Union address — President Obama firmly rejected the message of Donald Trump's campaign and said he expected as much from Americans.

"I'm pretty confident that the overwhelming majority of Americans are looking for the kind of politics that does feed our hopes and not our fears," Obama said at the time. "You know, talk to me if he wins."

Asked by Savannah whether he's now "worried" about Trump's candidacy, Obama replied, "I've seen all kinds of crazy stuff happen."

Obama also shared a pointed message for the Clinton campaign. "I think anybody who goes into campaigns not running scared can end up losing," he said.

"So, my advice to Democrats — and I don't have to give this advice to Hillary Clinton, because she already knows it — is you stay worried until all those those votes are cast and counted because you know, one of the dangers in an election like this is that people don't take the challenge seriously. They stay home. And we end up getting the unexpected."

Obama will address the Democratic National Convention Wednesday evening. On Tuesday, President Bill Clinton addressed the gathering, contrasting Hillary Clinton with her GOP rival and labeling her "the best darn change-maker" he's ever met.

RELATED: Bill Clinton tells America how he fell for Hillary

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When asked if he was personally frightened by the possibility of Trump having access to nuclear codes, Obama replied with a personal observation about the Republican presidential nominee.

"What I think is scary is a president who doesn't know their stuff and doesn't seem to have an interest in learning what they don't know," Obama said.

"I think if you listen to any press conference he's given, or listen to any of those debates, basic knowledge —about the world or what a nuclear triad is or where various countries are or, you know, the difference between Sunni and Shia in the Muslim world — those are things that he doesn't know and hasn't seemed to spend a lot of time trying to find out about," Obama explained.

In Obama’s last two addresses to his party’s convention, he spoke about changing the political tenor in Washington.

“That hasn’t happened,” he admitted. But he said his convention address Wednesday night will convey that he remains “profoundly optimistic about America’s future.”

Obama speaks two nights after the first lady delivered a universally praised address at the same gathering.

“I'm not going to hit that bar so let me concede top speech-making already to my wife, but I couldn't have been prouder of her,” he said. “The way she was able to remind all of us that where this really counts is the kind of message we're sending our kids about who we are and where we want to take this country.”

Michelle Obama didn’t call out Trump by name, but clearly addressed his negative campaign and its bullying tactics.

“She’s always been concerned about the tone and the tenor of politics. One of the things that we always talk about with our girls is how do you treat other people,” the president said.

But Obama also acknowledged that “one of the weird things about politics is sometimes we tolerate things that we would never tolerate in any other field or in our personal life. We wouldn't expect somebody to repeatedly say things that were demonstrably not true and somehow get a pass."

He said that applies to some of the personal attacks he’s received from Trump, who helped fuel the “birther” movement against Obama.

“I think that he is somebody who likes attention, maybe surprised himself that he got this far,” he said of Trump, who he suggested sees the presidency as a top-down job more than a collaborative one.

“That’s not how our founders designed our system. We’re not a government where some strong man orders people around and banishes enemies,” he said. “I think that it is important for us to remember that we live in a democracy. And by definition, then, the way we solve problems is by everybody participating and arguing and occasionally having to compromise.”

Obama also said Trump is a candidate far different than the typical Republican opponent.

“Absolutely. Well for one thing, he doesn't seem to have any plans or policies or proposals or specific solutions,” he said. “The good news is we’ve got a candidate in Hillary Clinton who has put out very specific plans and programs and is telling you exactly what she's going to do."

During a freewheeling news conference later Wednesday, Donald Trump lashed out at Obama, calling him "the most ignorant president in our history." Trump then said “the world is a mess” because of the way Obama has handled foreign policy.

“He has been a disaster as a president. He will go down as one of the worst presidents in the history of our county. It is a mess,” he said. “And I believe Hilary Clinton is even worse.”

Trump also appeared to encourage Russia to hack into Clinton's email server and release its findings to the public.

WATCH: Trump tells @KatyTurNBC to "be quiet" as she presses him on his hope that Russians have Clinton's emails. https://t.co/uBqOXeob3Y — NBC Nightly News (@NBCNightlyNews) July 27, 2016

"Russia, if you're listening, I hope you're able to find the 30,000 emails that are missing," he said. "I think you will probably be rewarded mightily by our press."