President Obama on Tuesday stood by his previous prediction that Donald Trump will not be president, and launched a fierce assault on the former real-estate mogul and reality television star as someone who doesn't have the experience or temperament to occupy the Oval Office.

"I continue to believe that Mr. Trump will not be president, and the reason is I have a lot of faith in the American people," he said. "I think they recognize that being president is a serious job — it's not hosting a talk show or reality show. It's not promotion or marketing. It's hard, and a lot of people count on us for getting it right."

Obama delivered the long anti-Trump monologue during a press conference in Rancho Mirage, Calif., where he had spent the last two days meeting with South Asian leaders.

Obama used that event to deliver his longest and most detailed argument against electing Trump to date. The president's decision to dump on Trump comes just days before Saturday's influential South Carolina primary, a race Trump is leading by wide margins in national polls.

Being president, Obama lectured, is not "pandering," it doesn't involve doing everything possible to get "yourself in the news every day."

Instead, the position as leader of the free world, involves "doing things that aren't popular and standing up for people who are vulnerable" and don't have powerful political interests backing them, Obama said.

Obama also attacked Trump's interviews on foreign policy as weak and his explanations for his policies shallow. He said the job of commander in chief involves "working with leaders around the world" and giving people at home and abroad "confidence that your know the facts and you know their names and a sense of history and you're not just going to play to the crowds back home and you're gong to solve problems."

Obama also predicted that "sensible" American people would not end up electing Trump because they wouldn't want to give him power to launch a nuclear war or send their sons and daughters into battle.

"When you get closer [to the election], reality has a way of intruding," he said. "… Whoever is standing where I'm standing now has the nuclear codes and can order 21-year-olds into a firefight, and has to make sure the banking system doesn't collapse."

Presidents, he said, have to take responsibility for "big countries that are falling apart and are looking for us to do something."

When it comes time to pulling the level for a particular candidate in November, he said, he has faith in the American people that they won't choose Trump.

"The American people are pretty sensible, and I think they'll make a sensible choice in the end," he said.