In the first of three debates before the November elections, Donald Trump and Hillary Clinton battled over who would make the best commander-in-chief, as Trump said Clinton did not have the "stamina" to be President, while Clinton assailed Trump's economic plans, saying they would be a boon to the wealthy.

"It's trickle-down economics all over again," Clinton said in a familiar refrain about Republican economic policies, which she labeled, "Trumped-Up, Trickle-Down."

Trump responded by accusing Clinton of looking to do one thing - increase taxes.

"You're going to raise taxes big league," Trump said, as he repeatedly tried to portray Clinton as the candidate of the status quo - essentially the incumbent - arguing she's responsible for the country going in the wrong direction.

"She's been doing this for thirty years," Trump said, "and now you're just starting to think of solutions."

Both candidates used a bevy of familiar phrases and arguments from their respective campaign speeches, as they tangled over Clinton's email server, Trump's tax returns and more.

"Maybe he's not as rich as he claims to be," Clinton said dismissively of Trump and his tax returns, using a Trumpian type line to go after the real estate mogul.

"It must be something really important, even terrible, that he's trying to hide," Clinton said.

Trump vowed to release his tax returns, but only when Clinton produces thousands of emails that she deleted from her time as Secretary of State.

"It's all words, it's all sound bites," Trump said as he dismissed a Clinton attack on his business record.

On recent unrest over a police shooting in Charlotte, North Carolina, Trump said Clinton was not doing anything to help quell violence in poor neighborhoods

"We need law and order in the inner cities," Trump said. "Secretary Clinton doesn't want to use a couple of words - 'law and order,'" Trump added

On the fight against terrorism, Trump agreed with Clinton on one issue, whether to stop people who are on the 'no-fly' list from buying firearms in the United States.

"I agree with you, when a person is on the watch list or the no-fly list," Trump said, "I tend to agree with that, quite strongly."