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.
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.