President Barack Obama responded to Donald Trump's latest critique of his administration with a chuckle on Thursday and appealed for voters to challenge the Republican nominee's "wacky ideas."

Trump said that Russian leader Vladimir Putin had "been a leader, far more than our president has been a leader" while slamming Obama during Wednesday's Commander-in-Chief Forum.

During his final press conference at the summit of the Association of Southeast Asian Nations (ASEAN), Obama was asked whether he would "defend" his legacy following Trump's these remarks.

"Do I care to defend...? OK, OK, respond," he said, laughing.

"As far as Mr. Trump, I think I've already offered my opinion," Obama said. "I don't think the guy's qualified to be president of the United States."

Obama urged the public and press "to just listen to what he says and follow up and ask questions about what appear to be either contradictory or uninformed or outright wacky ideas."

He added: “There is this process that seems to take place over the course of an election season where somehow behavior that in normal times we would consider completely unacceptable and outrageous becomes normalized. But I can tell you from the interactions I’ve had over the last eight or nine days with foreign leaders that this is serious business and you actually have to know what you’re talking about.”