Gregory Korte

USA TODAY

WASHINGTON — President Obama said Donald Trump's debate performance Monday night shows that he "doesn't have the preparation, the temperament, or the core values of inclusion" necessary to move the country forward.

Obama made his comments to radio personality Ryan Seacrest Tuesday as part of an voter registration outreach to millennial voters, urging young people not to sit out the presidential election.

By contrast, Obama said, Democrat Hillary Clinton was "well prepared."

"I am admittedly biased. I've worked with Hillary. I know her. She is well-prepared. She's got the right temperament for the job. She's well-respected around the world. She's serious. She does her homework. And she's got a vision to put people back to work and make sure the economy is working for everybody, and not just a few," he said.

Obama mostly stayed out of the post-debate spin machine during the primary elections, telling aides he often caught up on what happened in the morning papers, But his interview with Seacrest — and a separate interview with radio host Steve Harvey to be broadcast Wednesday — shows that he's much more willing to play a role as a Clinton campaign surrogate as the election nears.

Obama said his two biggest worries are nuclear proliferation and climate change, and that Trump fails the test on both. "That's why I get worried when somebody like Donald Trump start saying, 'Well, I don't necessarily know whether Japan or Korea should be protected by us. Maybe they should get their own nuclear weapon.' That shows somebody who doesn't pay attention to these issues, and you don't necessarily want close to the nuclear button."

And on climate change: "When you hear somebody like Trump say he thinks this is a plot from the Chinese, it’s a fraud, it’s a hoax — when 99% of scientists are saying, no, we have to do something about this, that worries me."

For Obama, the presidential debate trumps 'Monday Night Football'

Like most political junkies, Obama watched the debate from home — in this case, the Indian Treaty Room on the second floor of the White House, which Obama uses as a private study. "I'm sitting there, and I've got a big stack of work. And in between all the memos that I got I was enjoying what I thought was a pretty vigorous debate," he said.