On Tuesday Mr Trump abruptly ended an interview with veteran journalist Lesley Stahl, accusing her of “bias, hatred and rudeness”. He pre-emptively released a White House recording of the interview, which showed Stahl asking him if he was prepared for some “tough questions” and him responding: “I’m not looking for that, I’m looking for fairness”.
Watch: Barack Obama blasts Donald Trump for “crazy uncle” behaviour
Speaking at a drive-in rally in Miami as attendees hooted their horns in approval, Mr Obama said: "It’s a good idea of you’re running for re-election to say, here’s what I want to accomplish. What did Trump say? He got mad and walked out of the interview. The questions were too tough. Too tough?
“Miami, listen, if he can’t answer a question like, what would you like to do in your second term, then it’s our job to make sure he doesn’t get a second term.”
And stressing that Joe Biden, his former vice president for eight years, is genuinely tough while Mr Trump only plays tough, he said: “If you have to walk out of a 60 Minutes interview, you’re not going to stand up to a dictator."
"Joe Biden is tough, something you can’t really say about this president. He likes to act tough and talk tough – he thinks scowling and being mean is tough and being rude is tough. But when 60 Minutes and Lesley Stahl are too tough for you, you ain’t all that tough.
“If you’ve got to walk out of a 60 Minutes interview, then you’re never going to stand. up to a dictator. If you’re spending all your time complaining about how mean reporters are to you, you’re not going to stand up to Putin.”
Mr Obama again slammed his successor for his handling of the coronavirus pandemic, saying: "We literally left them a playbook that showed them how to respond before a virus reached our shores. It must be lost along with the Republican health care plan ... he doesn't even acknowledge that there's a problem."
He added: “Donald Trump isn't going to suddenly protect all of us. He can't even take the basic steps to protect himself.”
Friday saw the biggest number of new cases in the US since the pandemic reached American shores, with 83,000 new cases.
When the country last hit its daily record for coronavirus cases – 77,233 on 17 July, according to COVID Tracking Project – there were 18 states in the White House coronavirus task force's "red zone", meaning they reported more than 100 new cases per 100,000 people.
Now at least 33 states would be designated in the "red zone" for reporting more than 100 new cases per 100,000 people, based on data compiled by the New York Times.
Hours before Mr Obama’s speech on Saturday afternoon, Mr Trump spoke at a rally in North Carolina, the first of three he was holding in battleground states during the day.
Acknowledging reports of the spike in numbers, he again suggested this was only because of the high amount of testing, saying it was sometimes “foolish” to test for the deadly disease, which has cost the lives of more than 220,000 Americans so far.
He said: "You know why we have cases? It's because we test so much. In a lot of ways it's good, and in a lot of ways it's foolish.
"If we tested half, cases would halve."
Mr Obama’s speech certainly got the attention of Mr Trump, who has displayed an obsession with his predecessor for years. Predictably he gave his performance a bad review, tweeting: “Nobody is showing up for Obama's hate laced speeches. 47 people! No energy, but still better than Joe!”