The campaign arm of the House Democrats has filed an ethics complaint targeting Minnesota U.S. Rep. Tom Emmer and the National Republican Congressional Committee over the GOP’s use of campaign “trackers” to trail Democratic lawmakers inside congressional office buildings during the recent hearings over impeaching President Donald Trump.

The Democratic Congressional Campaign Committee asked the independent Office of Congressional Ethics to look into what it describes as “multiple instances in which the NRCC appears to have had its employees or others on its behalf chase and badger Democratic members of Congress in House office buildings.”

The complaint stems from the NRCC’s use of so-called trackers to follow Democratic lawmakers with cameras and pepper them with questions during the House impeachment debate in December. The tactic is commonly used by both parties on the campaign trail and during campaign events, but not inside the halls of Congress.

Emmer was named in the complaint as the elected chairman of the NRCC, the campaign arm of the House Republicans.

“As the NRCC is chaired by a member of Congress, these campaign activities in House office buildings are a clear violation of the House Ethics Manual,” read a news release from the DCCC.

Lucinda Guinn, executive director of the DCCC, alleged that Emmer broke House rules by using taxpayer funded facilities for political purposes.

Chris Pack, spokesman for the NRCC, called the complaint “a desperate and frivolous attempt by Nancy Pelosi’s political arm to distract from Washington Democrats’ collective failure to accomplish anything for the American people that they promised on the campaign trail.”

The nonpartisan Office of Congressional Ethics was established by Congress in 2008 to review allegations of misconduct by House members and potentially refer cases to the House Ethics Committee, which is evenly divided between Democrats and Republicans. Among its 10 current members is Minnesota Democrat Dean Phillips.