Four unidentified donors gave nearly $17 million last year to a conservative nonprofit group that distributed funds to organizations that backed President Trump’s inaugural committee and his Supreme Court nominees Neil M. Gorsuch and Brett M. Kavanaugh, according to tax documents.

Wellspring Committee, a politically active organization that funds conservative causes and groups, received $16.7 million in 2017 from four unnamed donors who gave between $250,000 and $8.9 million each, according to the group’s 2017 tax return, obtained by the advocacy group Citizens for Responsibility and Ethics (CREW) in Washington.

During the same period of time, the Northern Virginia-based group gave $14.8 million to another politically active nonprofit organization: the conservative Judicial Crisis Network (JCN), which spent millions of dollars backing the nominations of Gorsuch and Kavanaugh.

Wellspring also paid $919,900 for consulting work to BH Group, an Arlington-based company.

Little is known about BH Group, except that it gave $1 million to Trump’s inaugural committee a month before he was sworn in as president. In 2016, Wellspring Committee paid $750,000 to BH Group for public relations, tax records show.

Wellspring’s sole board member, Neil Corkery, declined to comment Tuesday.

The new tax filing highlights how unidentified donors can provide large sums to politically influential groups through complex webs of opaque groups and tax laws that allow contributors to remain hidden.

Because Wellspring and Judicial Crisis Network are set up as politically active nonprofit organizations, not as political committees, they are not required to disclose their donors publicly.

As a presidential candidate, Trump repeatedly criticized the role of big money in politics, particularly undisclosed donations.

“I want transparency,” he told Time magazine in August 2015. “I don’t mind the money coming in. Let it be transparent. Let them talk, but let there be total transparency.”

White House officials did not immediately respond to requests for comment.

BH Group has ties to influential conservative legal activists who have helped guide the Trump administration’s appointments of judges to federal and state courts, according to research by Robert Maguire, CREW’s research director.

Leonard Leo, executive vice president of the conservative legal network the Federalist Society, listed BH Group as his employer on a 2018 campaign finance disclosure, Maguire found.

Neither Leo nor the Federalist Society immediately responded to a request for comment.

It is unclear who is behind BH Group or what it does. But public filings show that the entity was one of the largest contributors to Trump’s inaugural committee, which raised a record amount of $107 million in private money, including from wealthy donors and corporations that cut six- to seven-figure checks.

Judicial Crisis Network has been a major recipient of Wellspring funds in the past, receiving $23.5 million from the group in 2016, according to tax records.

Most of the money Wellspring received that year came from a single $28.5 million donation — and the identity of that donor remains unknown publicly.

In 2017, JCN spent $17 million opposing President Barack Obama’s Supreme Court nominee, Merrick Garland, and supporting Gorsuch, according to the group. In 2018, JCN spent more than $5 million supporting Kavanaugh, running television and digital ads urging senators to confirm his nomination to the Supreme Court.

A representative of the group did not immediately respond to a request for comment.