Presumptive Republican nominee Donald Trump has called Hillary Clinton the most corrupt candidate in US history.
Mr Trump said the woman he will face in November’s election was a “world class liar” who had “perfected the politics of profit” while secretary of state.
“She gets rich making you poor,” he said in a broad speech in New York which also cast her as a destabilising force in the Middle East.
Mrs Clinton said the speech was “more hypocritical lies”.
“Economists on the left, right and centre all agree his dangerous economic policies would throw us back into recession,” said her spokesman.
Mr Trump is trailing in the polls and has had a tough couple of weeks, with much criticism within his own party for his response to the Orlando nightclub shooting.
But on Wednesday the businessman hit his Democratic rival with full force, saying she does not have the “temperament or judgement to be president” and she refuses to recognise the threat of radical Islamic terrorism.
“Her decisions spread death, destruction and terrorism… one deadly foreign policy decision after another,” he said of Mrs Clinton’s tenure at the State Department.
He said she wants to let Muslims into the country that want to “enslave women” and “put gays to death”.
Analysis – Anthony Zurcher, BBC News North America Reporter
Donald Trump promised a bare-knuckles speech with sweeping attacks on Hillary Clinton, and on Wednesday he delivered it.
He accused the Democratic presumptive nominee of criminal corruption. He called her a “world-class liar”. He offered a bullet-point summation of an anti-Clinton book written by a conservative commentator.
And he read a letter from the widow of a police officer killed by an undocumented immigrant who said the former secretary of state had the “blood of so many on her hands” and should “go to prison to pay for the crimes she has already committed against this country”.
Guided by his tele-prompter, Mr Trump offered a more focused, methodical attack on Mrs Clinton than he has normally produced in his stump speeches, but it wasn’t any less inflammatory – or prone to occasional exaggerations and misrepresentations.
If Mr Trump will be a more polished candidate with the change of campaign leadership announced this week, it seems clear he will be no less the brash, braggadocious candidate that stormed through the Republican primary season.
He attacked her on trade and said her support of the Trans-Pacific Partnership would cost the US thousands of jobs. She should be “scorned” for the trade deficit, he said.
“She ran the State Department like her own personal hedge fund, exchanging favours for straight-up cash.”
He said he would put American workers first and that his talent for creating jobs would help the US economy.
His speech comes a day after Mrs Clinton gave a blistering speech of her own on how Mr Trump would be “reckless” with the US economy.
“Every day we see how reckless and careless Trump is,” she said at a campaign event in Columbus. “Well that’s his choice. Except when he’s asking to be our president. Then it’s our choice.”
She has surpassed him in fundraising, starting June with $42m (£28m) in the bank; for Mr Trump it was $1.3m.
His campaign is transitioning as he pivots to the general election.
Controversial campaign manager Corey Lewandowski was fired this week and a few more campaign staff members joined his team.