Hillary Clinton clashed from afar with Donald Trump on the economy Monday, accusing him of peddling “old, tired ideas” that benefit the “really wealthy” – after the Republican nominee hammered the Democrats' “job-killing” agenda in a speech of his own where he unveiled a revised plan to jolt the economy by slashing taxes and regulations.

Trump delivered his economic address early Monday afternoon in Detroit, touting a plan he called a "night-and-day-contrast" with the “job-killing, tax-raising, poverty-inducing Obama-Clinton agenda.” 

Clinton returned fire hours later during a rally in St. Petersburg, Fla., saying her GOP rival has simply hired advisers trying to “make his old, tired ideas sound new.”

“His tax plans will give super big tax breaks to large corporations and the really wealthy,” she said. "He wants to repackage trickle-down economics."

Clinton said economists have already warned Trump’s policies “would throw us into recession.”

The sparks mark an abrupt return to the economy on the campaign trail, after a post-convention week during which Trump was caught up in controversies that had little to do with policy. 

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Despite Clinton’s accusations, Trump insisted Monday that his proposals would help lower- and middle-class Americans the most.

And he used the setting of the speech – Detroit – to draw a stark contrast with his rival’s approach.

“Detroit is a living, breathing example of my opponent’s failed economic policies,” said Trump, arguing bad international trade deals like NAFTA have resulted in record unemployment for the city and made a “total disaster” of the entire U.S. economy.

“Detroit is still waiting for Hillary Clinton’s apology,” he continued.

Trump vowed to create 500,000 jobs annually in the first seven years of his administration, while cutting business taxes and reducing federal regulations. Trump touted his plan to eliminate the estate tax, put a moratorium on new federal regulations and reduce the corporate tax rate from 35 percent to 15 percent, in his speech at the Detroit Economic Club. 

He also vowed to re-negotiate the decades-old North American Free Trade Agreement and warned that Clinton, if elected, would enact the Obama administration’s Trans Pacific Partnership, which critics argue would create even more disadvantages for the United States in international trade.

“We cannot let her win because that will be disaster for Detroit and everybody else,” Trump said. “Hillary Clinton’s Trans Pacific Partnership will be even bigger and even worse than NAFTA.” 

Clinton says she opposes the TPP in its current form. 

In an appeal to unemployed steel workers, miners and other blue collar workers whom Trump hopes to win over in Rust Belt states, the GOP nominee also vowed to end federal regulations that have throttled coal plants and eliminated jobs.

“The Obama-Clinton [agenda] has blocked jobs through anti-energy regulations,” he said. “The Obama-Clinton war on coal has cost Michigan jobs. Clinton said she will put coal miners out of business. … A Trump administration will end this war on the American worker and unleash an energy revolution that will bring vast new wealth.” 

The businessman and first-time candidate hopes to steady his campaign after a rough week in which he was criticized for comments about a Muslim-American family whose son, an Army captain, was killed in the Iraq War and for temporarily withholding his endorsement of House Speaker Paul Ryan in Tuesday's Wisconsin primary.

The Clinton campaign ripped into the proposed Trump plan earlier Monday morning, saying his tax breaks are only for the wealthy and includes no paid family leave or increase in the federal minimum wage.  

“We wanted to offer a look at how a Trump presidency would cause damage to the American economy and working families,” the campaign said in a 7-point memo. “We can be certain of this because we’ve read Trump’s ‘plans,’ listened to his words, reviewed what analysts have to say about what he wants to do. And it's the only logical conclusion.”

Trump, though, hammered Clinton Monday for seeking tax hikes as part of her economic agenda.

Clinton indeed has proposed raising taxes on the highest-income earners, including a surcharge on multimillionaires, but analysts have found lower-income earners would see little change beyond measures like additional tax credits for expenses like out-of-pocket health care costs.

In his speech Monday, Trump also announced his plan to allow parents to fully deduct the cost of childcare from their taxable income. He also called again for boosting domestic energy production -- a plan his campaign estimates can add $6 trillion in local, state and federal revenue over the next four decades.

The Associated Press contributed to this report.