Donald Trump is once again taking the fight to Democrats and Hillary Clinton.

During a week in which the Republican presidential nominee has been attacking Clinton for disparaging half of his supporters as "deplorables," Trump plans to roll out a new proposal that treads deep into the core issues that Clinton and other Democrats regularly campaign on: making child care more accessible and affordable.

In a speech Tuesday evening in suburban Philadelphia, Trump is expected, according to campaign aides, to go into more detail on a proposal he originally laid out last month in a wide-ranging economic speech — allowing parents to deduct the average cost of child care from their taxes.

How the plan works

Trump's expanded plan would allow parents to deduct the average cost of child care from their taxes. The campaign says this is focused on "working and middle-class families," though its income caps — $250,000 for individuals and $500,000 for couples — far exceed most people's definition of working class.

After his economic speech last month, Trump was criticized for a plan that didn't do anything for those who don't earn enough to pay federal income taxes. They wouldn't be able to take advantage of the deductions, and because child care costs what it costs, it has an outsize impact on the poor.

To address this, Trump's campaign unveiled child care rebates — up to $1,200, staffers say — to provide benefits to people who currently don't earn enough to pay federal income taxes.

The Trump campaign says that stay-at-home parents would also be eligible for the same tax deductions working parents currently receive.

As CNBC found in its analysis when Trump's plan was unveiled last month, Trump's plan "would create a substantial tax break for working parents, but further widen the deficit." That's because:

"On average, households with a woman working outside her home and taking care of a child under 15 paid an average $127 a week on child care, according to a Census Bureau analysis of 2010 data. That works out to about $6,600 a year. With some 24 million households in that category, the child-care tax break would cost the government $158 billion a year."For families paying for child care, the current tax break offers little relief. Only 3.5 million tax returns claimed the existing child-care tax credit for the 2010 tax year, according to IRS data, saving those households $1.9 billion. (Nearly 10 million returns claimed a separate tax credit for all parents, whether or not the family had child-care expenses, for another $14 billion in tax savings.)"So total out-of-pocket child-care costs amounted to about $142 billion, which a Trump administration would either have to make up with higher taxes or add to the budget deficit."

Along with all this, the campaign is now promising to "guarantee" six weeks of paid maternity leave. (Paternity leave is not mentioned.)

Clinton's proposal would be open to fathers as well. She also wants to institute a hard cap on families' child care costs, at 10 percent of their overall income.

Tax-free savings accounts

Trump would also create a Dependent Care Savings Account, which would allow "tax-deductible contributions and tax-free appreciation year-to-year," according to a campaign-provided fact sheet. What's more, the government would match half of the first $1,000 deposited per year.

That could come at a whopping cost. There are some 124 million households in the U.S., about 43 percent of which include children. That's more than 50 million households. If all of those families put in $1,000 per year, it would cost the government $25 billion annually. Even if half of all families contributed to it, that's still a big price tag, and the Trump campaign outlines no way to pay for it. Not to mention that that kind of benefit doesn't help the families who can't afford to put that much in per year.

Trump campaign policy adviser Stephen Miller told NPR's Sarah McCammon that a Trump administration would focus on fraud to finance the family leave portion. Miller's estimate was $5.3 billion in unemployment insurance fraud, which the campaign believes it can recoup half of. Republicans wary of increasing government spending frequently suggest funding new proposals by saying they will eliminate fraud.

"We estimate we can easily recover $2.5 [billion] for paid leave," Miller said.

That still would leave a sizable gap in how to pay for the overall plan. Miller added, "The rest is paid for through comprehensive tax and economic reform." And the campaign believes it would be "deficit-neutral." But if that's based on "growth," that can always be a murky calculation.

Trump has already overhauled his tax plan once during this election campaign. One outside analysis of his initial tax plan estimated a 10-year cost to taxpayers of $9.5 trillion. An economic adviser to Trump estimated in August his updated plan would cost $3 trillion over a decade.

The Trump campaign says Trump's daughter Ivanka was deeply involved in coming up with this proposal. It echoes a notable line from her speech at the Republican National Convention in July, when she told Republicans that Trump would "focus on making quality child care affordable and accessible for all."

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