Michelle ObamaMichelle LeVaughn Robinson ObamaLizzo donates lunch to hospital workers battling coronavirus Biden could be picking the next president: VP choice more important than ever Lobbying world MORE mocked Donald TrumpDonald John TrumpMilitary personnel to handle coronavirus patients at facilities in NYC, New Orleans and Dallas Navy hospital ship USNS Comfort has total of 20 patients: report Fauci says that all states should have stay-at-home orders MORE on Tuesday for complaining about his microphone at last week’s debate.

While campaigning for Hillary ClintonHillary Diane Rodham ClintonFormer Obama adviser Plouffe predicts 'historical level' of turnout by Trump supporters Poll: More Republican voters think party is more united than Democratic voters Whoopi Goldberg presses Sanders: 'Why are you still in the race?' MORE in Charlotte, N.C., the first lady said that Democratic presidential nominee Hillary Clinton is more determined than Trump.

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“I’ve watched her, when she gets knocked down, she doesn’t complain, she doesn’t cry foul,” Obama said while leaning down to tap her microphone. “No, she gets right back up.”

The Commission on Presidential Debates admitted days after the first debate that there had been "issues" with Trump’s audio levels in the hall. He has seized on the admission and suggested that he was intentionally given a defective microphone.

The first lady also attacked the GOP nominee over his tax returns.

“We need someone who’s honest and plays by the rules, because not paying taxes for years and years while the rest of us pay our fair share does not make you smarter than the rest of us,” the first lady said.

“No, we need a president who will choose to do what’s best for the country even when it doesn’t personally benefit them.”

The New York Times revealed on Saturday that Trump reported a $916 million loss on his 1995 tax returns, which could have allowed him to forego federal income tax for up to 18 years. His tax payments after 1995 are not publicly known because Trump has not released any tax records.

Trump and his surrogates responded to the report and the ensuing criticism by arguing that taking advantage of the tax laws was a savvy move for the businessman and arguing that Trump is well-positioned to reform the tax system.

“As a businessman and real estate developer, I have legally used the tax laws to my benefit, and to the benefit of my company and my employees,” Trump said on Monday, adding that he “brilliantly used those laws.”

"I’m working for you now, I’m not working for Trump,” he added.

Obama on Tuesday made clear that she wasn’t buying the argument.

“The presidency doesn’t change who you are, it reveals who you are,” the first lady said.