On the eve of the 2016 election, Obama told supporters that he would be offended if America chose a flamboyant reality TV star to succeed him.

But the Americans did it.

Four years later, Obama returned to the Democratic Congress by speaking online from the American Revolutionary Museum in Philadelphia on the evening of August 19.

Not only does Obama see this year's election as an opportunity to revive the international programs and agreements that Trump abandoned, it also to rewrite the story of America and its values.

However, that view was undermined because after he left office and the Americans chose a new president the complete opposite of him.

"Obama and many of his aides believe the country can recover after four years in power, but if Trump is in power for another four years, the damage cannot be saved," said Jen Psaki, former director of transmission.

The main goal in Obama's 15-minute speech did not appear to be to praise Biden but to criticize Trump.

"Donald Trump is not adapting himself to the job because he cannot do it," Obama said.

Biden often emphasizes his time as vice president under Obama while campaigning, to attract young voters and especially African-Americans, the group of voters that helped him win the round.

Although resigned for nearly four years, Obama is still one of the most popular politicians in America.

However, history shows that American presidents cannot always help the people they support get "loved".

Obama's desire to see Trump defeated may be even stronger than his determination to help Biden, especially when there are personal disagreements between the two.

Trump's attention to Obama is strategic.

"I think President Trump sees Biden's strongest card as he used to work for Obama. If Joe keeps on Obama's achievements, Trump will show everyone that Obama is not as good as many think."

Obama and his team spent a lot of time wondering where things went wrong when Trump was elected in 2016, wondering if they misjudged the country's atmosphere and their own achievements.

A Senate report released this week affirms Russia intervened in the 2016 election with the goal of helping Trump win and Trump's campaign is also willing to help, despite special counsel Robert

For Obama, August 19 is an opportunity to correct what he considered the mistake of four years ago.