BLACKWOOD, N.J. — Democratic presidential candidate Hillary Clinton attacked Republican Donald Trump’s tax plans Wednesday and prodded him to release his income tax returns before the November election.

At a rally to launch her New Jersey primary campaign effort, Clinton told a South Jersey crowd of hundreds of people that Trump’s tax plan was “written by a billionaire for billionaires” and would hurt middle-class Americans.

“I believe we can both grow the economy and have a fairer economy,” Clinton said to cheers from the crowd inside a gymnasium at Camden County Community College in Blackwood, near Camden.

Clinton also prodded Trump to release his tax returns. On Tuesday, Trump told The Associated Press he did not plan to make his returns public before November because he did not expect an Internal Revenue Service audit to be completed by then. He said he would release the documents once the audit is done.

“You’ve got to ask yourself why he doesn’t want to release them,” Clinton said. “We’re going to find out.”

Clinton said it’s “expected” that each party’s presidential nominee will release his or her tax returns publicly. Her campaign website has links to her and husband Bill Clinton’s tax returns for 2007 through 2014.

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Clinton argued that Trump’s proposed tax cuts would add trillions of dollars to the national debt while only benefiting the wealthy. She said the lost revenue would be “enough to make Social Security solvent.”

Trump’s plan, as posted on his campaign website, calls for consolidating the IRS’ seven tax brackets into four, and reducing the highest income tax rate from 39.6 percent to 25 percent.

Trump would cut the business tax rate from 35 percent to 15 percent, and eliminate federal income taxes for individuals making less than $25,000 and married couples earning below $50,000

A study by the nonpartisan Tax Foundation, a Washington, D.C.-based think tank, said Trump’s initial proposal could add an estimated $10 trillion to the federal deficit over the next 10 years.

Clinton has proposed a 30 percent minimum tax rate on individuals who earn more than $1 million, and would raise the estate tax rate by 5 percent, to 45 percent.

A Tax Foundation study said the plan would generate $498 billion in tax revenue over the next decade, but also would “reduce the economy’s size by 1 percent in the long run.”

On Sunday, Trump said on NBC’s “Meet the Press” that he planned to adjust the plan to “make sure the middle class gets good tax breaks.” He suggested he would raise taxes on the wealthy, saying “it really should go up.”

Facing backlash from Republicans alarmed by talk of a tax increase, Trump clarified his position in a Twitter posting Monday, saying any changes to his plan would “still be lower than current” tax rates.

The Trump campaign did not immediately respond to an email seeking comment about Clinton’s remarks about Trump.