“Don’t get frustrated and cynical about our democracy” even though “Lord knows it’s frustrating,” he pleaded at the tail end of a question-and-answer session at the social networking titan’s home base on Wednesday.

Obama listed a series of his achievements, including his landmark health law and getting two women on the US Supreme Court, but warned young voters who helped win him the White House two years ago that he needed them to face challenges like the country’s debt and deficit struggles.

“I can’t do it by myself. The only way it happens is if all of you still get involved, still get engaged,” said Obama, whose once sky-high approval ratings have slipped to below the critical 50-per cent threshold in many polls.

“I know that some of you who might have been involved in the campaign or been energised back in 2008, you know, you’re frustrated that, gosh, it didn’t get done fast enough, and it seems like everybody’s bickering all the time.”

But “rather than be discouraged, I hope everybody is willing to double down and work even harder,” the president said after taking questions from Facebook founder Mark Zuckerberg, his employees, and an online audience.

Obama’s visit, part of a barnstorming tour that includes major fundraising stops, aimed to recapture twin engines of his 2008 White House run, when his campaign tapped into social media as never before and rallied young voters.

The president, who faces fired-up Republicans and a likely hard battle to a new four-year term, opened a frequently professorial back-and-forth by joking that he at least got Facebook’s youthful founder to dress up.

“My name is Barack Obama, and I’m the guy who got Mark to wear a jacket and tie,” the president quipped.

“Thank you,” Obama said with a chuckle as Facebook employees rewarded him with a chorus of laughter. “I’m very proud of that.”