A nonprofit group believed to be the League of United Latino American Citizens (LULAC) used illegal corporate contributions to secretly aid Hillary Clinton’s 2008 campaign, according to federal court documents.

Democratic donor and District of Columbia businessman Jeffrey Thompson pleaded guilty on Monday to funneling millions in illegal donations to local and federal candidates, including Clinton in 2008.

Thompson said in his plea agreement that he financed a $600,000 "shadow campaign" for Clinton using funds from his D.C.-based for-profit corporation D.C. Healthcare Systems Inc.

The money was routed through Troy White, a marketing director who pleaded guilty to insurance violations last September, and through a group identified in the plea agreement as "Civic Organization A."

The unnamed group is LULAC, the Washington Post reported on Tuesday.

A LULAC spokesperson would not immediately confirm whether it was "Civic Organization A" when contacted by the Washington Free Beacon. However, she said the group was cooperating with federal investigators on the case.

"We are cooperating with the investigation, but we can’t comment on any specific matters," said LULAC spokesperson Paloma Zuleta.

She referred further questions to LULAC counsel Manuel Escobar who did not return a request for comment.

LULAC, a Hispanic advocacy group headquartered in Washington, D.C., is a 501(c)(4) and subject to Internal Revenue Service limits on its political activities and expenditures.

According to Thompson’s plea agreement, a senior Clinton campaign adviser asked him in February 2008 to fund paid street teams that would assist the campaign.

The adviser is believed to be long-time Clinton aide Minyon Moore, the Washington Post reported.

Moore allegedly introduced Thompson and an unnamed Texas Clinton supporter affiliated with LULAC, with the understanding that the two would work to organize teams of paid Clinton canvassers recruited from LULAC’s membership ranks.

The canvassers would distribute materials created by the Clinton campaign in Texas, according to the documents.

Thompson transferred $233,000 through an intermediary to pay for the services.

After the Texas primary, Thompson, working in cooperation with LULAC, transferred additional funds to pay for similar operations in Pennsylvania, Indiana, and North Carolina, according to the filings.

Moore appeared to be in regular communication with Thompson and the LULAC official. In April 2008, she emailed Thompson with details about the Clinton campaign’s strategy in the North Carolina primary, writing, "This is what [the campaign] will need in NC—please advise."

In May 2008, Thompson provided additional funds to pay for a pro-Clinton street team effort in Puerto Rico shortly before the primary.

The LULAC official emailed Thompson photos of the rallies on May 31, 2008, writing "We bought everything or made it here [in] PR. All the white shirts waving signs or flags are our people."

The official added: "The caravan of vans together with the 18 wheeler sound system is unbelievable. … See you soon."

During Clinton’s visit to Puerto Rico leading up to the primary, she was photographed riding at the front of a caravan of vans on May 31, 2008.

A spokesperson for Clinton did not respond to questions about who paid for the caravan she was photographed in.

Thompson also sent funds to LULAC to help pay for a demonstration outside of the Democratic National Committee headquarters in April 2008, to protest the DNC’s decision not to seat delegates from Florida. The DNC’s decision was opposed by the Clinton campaign.

While rally organizers told reporters at the time that the protest was not in support of any specific candidate, many of the speakers were Hillary Clinton supporters.

Thompson agreed to bankroll the lodging, transportation, meals and promotion for the rally, according to the plea agreement. He transferred $150,000 to the group’s bank account on May 24, 2008, according to records.

That same day, LULAC announced publicly that it was paying for these expenses itself, according to a 2008 Huffington Post article.

Thompson also sent $50,000 to the group to help pay for a lawsuit in Texas to challenge a voting rule known as the "Texas Two-Step" that was opposed by the Clinton camp.

LULAC won its lawsuit against the "Texas Two-Step" on Aug. 25, 2009, according to a press release on its website.

Federal prosecutors have reportedly spent years piecing together the case against Thompson. He is also accused of funding a shadow campaign for Washington, D.C. Mayor Vincent Gray and members of Congress.

Thompson claims Gray was aware of his illegal fundraising. He did not say whether Clinton or additional top campaign aides knew about the shadow campaign scheme.

Under the terms of Thompson’s guilty plea, he faces up to 18 months in prison for federal campaign violations and up to six months in prison for local campaign violations.