Barack Obama takes down Donald Trump as he campaigns for Hillary Clinton in Philadelphia

Relaxed president ridicules Republican candidate for not letting ordinary people on his golf courses

Barack Obama delivered a withering attack on Donald Trump during a solo campaign appearance on behalf of Hillary Clinton in Philadelphia, ridiculing the Republican's claim to represent ordinary voters.

Mr Obama's easy riffing was a reminder of his potent force on the campaign trail and provided Democrats with a much needed lift after days consumed by details of their candidate's health.

"This is a guy who spent 70 years on this earth showing no concern for working people," said Mr Obama. "He spent most of his life trying to stay far away from working people. He wasn't going to let you on his golf course."

Mr Obama cited the successes of his two terms in office as signs of progress that Ms Clinton would most definitely continue. He lauded his diplomatic successes, health care reforms, and the killing of Osama Bin Laden.

His talk of a rebounding economy was reinforced by new data released by the Census Bureau showing household incomes increasing at their fastest ever rates.

“By so many measures America is stronger and more prosperous than when we started out on this journey together,” Mr Obama said. “Last year across every age, every race in America, incomes rose and the poverty rate fell.”

He added: “Let’s face it, Republicans don’t like to hear good news right now, but it’s important to understand this is a big deal. … Thanks, Obama.”

Mr Obama went on to discuss the glaring difference between Ms Clinton and her rival, Donald Trump, and repeated his view that the New York businessman was not fit “in any way, shape, or form” to be commander-in-chief.

With Ms Clinton recovering from pneumonia, the appearance of a relaxed, almost giddy president celebrating his successes will stand in stark contrast to Republican rallies, with their talk of a failing nation, financial woes and global insecurity.

Despite the tough week, the Clinton campaign will likely benefit from the campaign prowess and soaring popularity of the president. According to the latest Washington Post-ABC News poll, Mr Obama has a remarkable approval rating of 58 per cent – an eight-year high for the president. Ninety per cent of Hillary Clinton supporters are happy with the job Mr Obama’s done so far.

Mr Obama ridiculed Mr Trump's claim to speak for ordinary working people (AP)

The incumbent president’s approval rating tends to suggest the likely favour of voters on election day. So Mr Obama’s support can go a long way at this stage in the campaign.

Although the president’s appearance had been planned long in advance, it could not have been better timed. The controversy surrounding Ms Clinton’s health and the evaporation of her lead in the polls suggests the election still has a long way to run.

Ms Clinton has also received criticism from the Trump campaign for her remark about the New York businessman’s appeal to hate groups, saying half of his supporters could be grouped in a “basket of deplorables”.

But Mr Obama called out the apparent double standard from the press, accusing pundits of grading the presidency “on a curve” and said Ms Clinton was “subjected to more scrutiny and ... more unfair criticism than anybody out here”.

“We have become so partisan, our standards for what’s normal have changed,” he said. “And Donald Trump says stuff everyday that used to be considered as disqualifying for being president. And yet, because he says it over and over and over again, the press just gives up. …

“So, the bottom line is that we cannot afford certainly to treat this like a reality show. We can’t afford to act as if there is some equivalence here.”