The House Ethics Committee said Monday it is reviewing charges lodged against two high-profile Democratic lawmakers and a senior Democratic aide.

The lawmakers facing an ethics review are Rep. John Conyers Jr. (Mich), the ranking Democrat on the Judiciary Committee and the longest-serving sitting House member, and Rep. Ben Ray Luján (N.M.), chairman of the Democratic Congressional Campaign Committee. The staffer is Michael E. Collins, chief of staff to Rep. John Lewis (D-Ga.).

Statements released Monday by the Ethics Committee did not detail the allegations against the three men, which were forwarded to the committee by the independent Office of Congressional Ethics based on a “substantial reason to believe” a violation has occurred.

The cases will come up for further review on Aug. 9, at which point the Office of Congressional Ethics report in each case will be made public and the Ethics Committee can launch a more serious investigation, dismiss the allegations or extend its review.

“The Committee notes that the mere fact of a referral or an extension, and the mandatory disclosure of such an extension and the name of the subject of the matter, does not itself indicate that any violation has occurred, or reflect any judgment on behalf of the Committee,” the panel said in each case.

A spokesman for Luján, who is in charge of electing Democrats to the House, said the investigation is linked to a complaint filed by a conservative watchdog group last year about the sit-in led by Democrats on the House floor in response to the Orlando nightclub shooting.

The Foundation for Accountability and Civic Trust said Luján improperly used images of Democrats on the House floor in fundraising emails. “Do you stand with us?” one Luján solicitation read. “Chip in $24 toward our emergency fundraising goal — $1 for every hour we’ve been in the well of the House chamber demanding action.”

“This announcement is the result of a frivolous complaint, filed by a highly partisan outside group about activities during the sit-in last year — a complaint that is without merit,” said spokesman Joe Shoemaker. “Congressman Luján is committed to abiding by House rules, is confident he has done so in this case, and looks forward to a timely resolution by the Ethics Committee.”

The Conyers investigation appears to concern the departure of a former staffer to the 88-year-old congressman. On Feb. 8, the OCE found the aide, Cynthia Martin, “received compensation from the House of Representatives at a time when she may no longer have been working for the House” for several months last year — a violation of House rules that could implicate Conyers if he approved or was aware of improper payments.

“This is not a new controversy, but rather involves the same matter that the Office of Congressional Ethics released back in February,” said a statement released Monday by a Conyers spokeswoman. “Rep. Conyers’ office has worked diligently at all times to comply with the rules, is cooperating with the Ethics Committee, and is confident that this matter can be swiftly resolved.”

Brenda Jones, a spokesman for Lewis, did not describe the nature of the allegations against Collins, but said that Collins “respects the process of ethics review and is cooperating with the committee.”

The Foundation for Accountability and Civic Trust filed a separate complaint against Collins in January, alleging that he improperly held dual roles on Lewis’s official staff and his campaign and that in the latter role, he accepted an excessive salary of $27,495. Collins denied any wrongdoing at the time.