By RICHARD LARDNER, Associated Press

WASHINGTON (AP) — Anonymous donors gave more than $79 million to a liberal nonprofit during President Donald Trump's first year in office, helping fuel opposition to Judge Brett Kavanaugh's Supreme Court nomination and build support for a slew of other progressive causes.

The contributions in 2017 to the Sixteen Thirty Fund, a tax-exempt social welfare organization, represented a sharp increase over the $21 million it collected in 2016 when President Barack Obama still occupied the White House, according to newly released federal tax records.

Among the more than 40 initiatives it has backed is Demand Justice, an advocacy group formed in May that became one of the leading voices on the left against Kavanaugh's nomination. The group launched stopkavanaugh.com after Trump announced in July he'd picked Kavanaugh to replace Supreme Court Justice Anthony Kennedy. The website described his nomination as "the biggest fight of our lifetimes."

Kavanaugh was sworn in as the 114th Supreme Court justice in early October after an acrimonious confirmation process that involved a woman testifying that Kavanaugh sexually assaulted her decades ago when both were teenagers. Kavanaugh denied the claim.

It's unclear, however, how much of the millions in contributions to the Sixteen Thirty Fund went to Demand Justice. The group is structured in such a way that it doesn't have to file annual tax returns. That's because it's "fiscally sponsored" by the Sixteen Thirty Fund, which does file federal tax returns but doesn't have to disclose the identities of its donors. The organization has previously said it strictly follows all laws.

Social welfare organizations are permitted to engage in limited political activities as long as politics isn't their primary focus. Known by their IRS designation as 501(c)(4)s, they often include civic-minded groups such as homeowner associations and volunteer fire departments.

Federal rules permit these organizations to shield the identities of the donors. But critics say this allows wealthy benefactors to wield considerable influence without having to reveal who they are, unless they choose to.

The Wellspring Committee, a separate social welfare group that backs conservative causes, last year gave nearly $15 million it received from anonymous donors to the Judicial Crisis Network, a Republican-aligned advocacy group that supported Kavanaugh's Supreme Court bid.

Beth Kanter, a spokeswoman for the Sixteen Thirty Fund, said that as "a fiscal sponsor, we can be nimble and get projects off the ground quickly in a way that donors can't do on their own." She also said the 2016 elections "changed the landscape and raised the stakes for our funders and projects."

The Sixteen Thirty Fund's president is Eric Kessler, the founder of Arabella Advisors and a former Clinton administration official. The executive director of Demand Justice is Brian Fallon, a former top aide to Senate Minority Leader Chuck Schumer, D-N.Y., who later advised Hillary Clinton's presidential campaign in 2016.

The Sixteen Thirty Fund sponsors a sprawling network of groups, according to information filed with the District of Columbia's Department of Consumer and Regulatory Affairs. They include Michigan Families for Economic Prosperity, Stop Payday Predators and Protect the Investigation, which was registered in June and aims to "educate the American people" about the importance of special counsel Robert Mueller's investigation into possible coordination between Russia and the Trump campaign during the 2016 election.

The Sixteen Thirty Fund's 2017 tax return lists 69 separate donations totaling $79.3 million. The largest individual contribution was $37 million and the smallest was $5,000.

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Follow Richard Lardner on Twitter at http://twitter.com/rplardner