The Campaign Legal Center (CLC), a nonpartisan watchdog based in Washington, D.C., filed a complaint on Tuesday with the Federal Elections Commission (FEC), claiming that the Trump campaign illegally concealed $170 million in spending.

The CLC alleges that the Trump campaign and an authorized joint-financing committee funneled millions to various “pass through” companies, without disclosing their specific expenditures to the public. One of the firms receiving the money, American Made Media Consultants (AMMC), is founded by former Trump campaign manager and current social media strategist Brad Parscale.

These “pass through” companies could then use the funds to pay Trump campaign members, associates and family members. The complaint urges the FEC to launch a probe into the campaign, but it's unlikely that such an investigation would be concluded prior to November’s election.

“This illegal conduit scheme leaves voters in the dark about the entities working for the Trump campaign, the nature of their services, and the full amount they are paid,” said Brendan Fischer, the CLC’s director of federal reform. “We don’t know all of what is being hidden by this scheme, but we do know that it violates the law.”

Trump campaign spokesman Tim Murtaugh defended the payments to AMMC.

“AMMC does not earn any commissions or fees. It builds efficiencies and saves the campaign money by providing these in-house services that otherwise would be done by outside vendors,” Murtaugh said in a statement. “The campaign reports all payments to AMMC as required by the FEC. The campaign complies with all campaign finance laws and FEC regulations.”

Trump is being investigated for campaign finance violations by Manhattan District Attorney Cyrus Vance Jr., who is seeking eight years of Trump's financial records and taxes from his longtime accounting firm. Vance is trying to determine whether Trump was directly involved in multiple illegal hush-money payments to silence women he had affairs with prior to the 2016 election.