Cambridge Analytica, a firm that helped with the Trump campaign’s data operations, sent foreign workers to advise Republican campaigns in the U.S. for the 2014 elections, former employees told the Washington Post for a report published Sunday.

Election rules in the U.S. dictate that foreign nationals cannot partake in the “decision-making process” of a campaign and can only serve in a minor role. However, foreign nationals employed by Cambridge Analytica helped decide which voters to target and craft messages sent to those voters, according to the Washington Post.

Following the Washington Post’s report, progressive watchdog group Common Cause filed complaints with both the Federal Election Commission and the Justice Department, calling on both entities to investigate whether Cambridge Analytica violated election rules by employing foreign nationals to advise campaigns in the U.S.

Cambridge Analytica has come under fire recently due to reports that the firm improperly obtained data from Facebook for its election work. Special counsel Robert Mueller is examining links between the firm and President Donald Trump’s campaign, as well as the campaign’s use of voter data.

Read the Washington Post’s full report here.