WASHINGTON (AP) — The watchdog group Common Cause filed a complaint with the Federal Election Commission on Wednesday, alleging that Our Revolution, a political nonprofit organization founded by Bernie Sanders, violated campaign finance law by accepting donations in excess of federal limits while boosting his White House ambitions.

The complaint comes after The Associated Press reported earlier this month about the donations.

Our Revolution has denied any wrongdoing. A spokesman declined to comment. Sanders’ campaign also did not respond to a request for comment.

The campaign finance act says groups established by federal officeholders or candidates cannot raise money for federal electoral activity that exceeds the limitations of the law. Those contributions are currently set at $2,800 for candidates and $5,000 for political action committees.

Our Revolution has taken in nearly $1 million from donors whose contributions exceeded those limits and whose identities it hasn’t fully disclosed, according to tax filings for 2016, 2017 and 2018. Much of it came from donors who contributed six-figure sums.

The group has paid for some social media ads backing Sanders’ campaign and is working to turn out voters who will support the senator in the Democratic presidential primary. The group will not have to disclose its 2020 spending until after the election.

Candidates are barred from accepting contributions from corporations, labor unions, federal contractors and foreign nationals. The group does not fully disclose who its contributors are.