WASHINGTON — Ivanka Trump has urged lawmakers writing a tax overhaul to include a deduction for child care expenses, but with a price tag of as much as $500 billion over a decade she may have trouble finding support in Congress.

Members of the House and Senate met with the president’s eldest daughter in the Roosevelt Room at the White House last week to discuss her proposed child care tax benefit, according to a person with knowledge of the meeting. President Donald Trump said earlier this month that he would soon propose a comprehensive tax overhaul, without offering any details.

Ivanka Trump’s involvement in tax negotiations between the White House and congressional Republicans is a signal of her influence with her father despite having no formal role in his administration. Dina Powell, the former Goldman Sachs Group Inc. executive who is an economic adviser to the president, is helping Trump to ensure a tax overhaul includes both the child care benefit and a requirement that employers provide paid maternity leave, policies that she pressed her father to embrace on the campaign trail last year.

“Ivanka is really pushing that none of it gets passed unless it includes the child care tax plan,” said Sheila Marcelo, founder of www.care.com, a website to find babysitters and other caregivers. “She and Dina Powell are really pushing to make sure it gets included.”

In January, Ivanka Trump invited Marcelo to dinner at the home of Wendi Deng, the ex-wife of Twenty-First Century Fox Inc. co-Chairman Rupert Murdoch, to discuss her plans to focus on women’s empowerment during her father’s presidency. The dinner included top female executives, including International Business Machines Corp. Chief Executive Officer Ginni Rometty, Xerox Corp. Chairman and CEO Ursula Burns, and Deloitte CEO Cathy Engelbert.

It’s not clear whether Ivanka Trump is finding much appetite on Capitol Hill for her proposal. A deduction for child care expenses is both costly and regressive because it would favor wealthier families with two working parents. The deduction would cost the federal government $500 billion in revenue over a decade, according to an estimate by the Tax Foundation, a politically conservative, nonprofit research group.

“The child care proposal is generous and broad; almost everyone with young children will get some benefit from it. However, the largest benefits will go to relatively affluent dual-income families using paid child care,” said Alan Cole, an economist with the Tax Foundation.