President Trump’s nominee to lead the Department of Homeland Security, Kirstjen Nielsen, has been guided through her Senate confirmation process by a private consultant who represents companies seeking millions in DHS contracts, an arrangement that creates conflicts of interest, according to a government-ethics watchdog group as well as current and former national security officials.

The consultant, Thad Bingel, is co-founder of the Command Group, a prominent lobbying and consulting firm that offers "full spectrum solutions related to safety, security and intelligence" to clients "on six continents."

As Nielsen made the rounds on Capitol Hill last month ahead of a vote on her nomination by the Senate Homeland Security committee, she was joined by DHS officials as well as Bingel, according to Senate staffers, who said they received no advance notice of his attendance and weren’t sure why he was there.

“He was introduced to our staff as Nielsen’s aide,” said one Senate staffer, speaking on the condition of anonymity to discuss the closed-door meeting.

During presidential transitions, unpaid consultants often serve as “sherpas” to help steer a nominee through the confirmation process. But it’s almost unheard of once an administration has legislative political appointees in place whose job it is to perform that function, current and former DHS officials said.

“It’s highly unusual that you would have someone leading confirmation preparations from outside the government, especially after the administration has been in place almost a year,” said John Cohen, a longtime security and intelligence official who has served under Republican and Democratic administrations.

Nielsen and Bingel worked together as sherpas for John Kelly, the White House chief of staff, after Trump nominated him to lead DHS. Kelly hired Nielsen to be his chief of staff at DHS, then brought her to the White House as his deputy. Bingel remained at his consulting firm.

In copies of recent emails viewed by The Washington Post, Bingel was included in internal communications between DHS officials and White House staffers working to advance Nielsen’s nomination. The messages involved nearly a dozen officials, and Bingel was the only person who wasn’t a government staffer.

The exchanges show Bingel, a private contractor, leading briefings to DHS officials. Bingel, whose role in Nielsen's nomination was first reported by Cyberscoop, did not respond to interview requests.

A DHS official referred questions about Bingel to the White House.

“There’s nothing inappropriate or new about an individual volunteering their time to help prepare a nominee for the Senate confirmation process,” said Hogan Gidley, a White House spokesman, in a statement.

Cohen, who was a homeland security adviser to former Massachusetts governor Mitt Romney, said he could not remember another instance of DHS employees being assigned tasks to prepare a nominee by a private consultant, or sharing sensitive communications about a nominee through nongovernment servers.

Bingel was chief of staff of U.S. Customs and Border Protection under President George W. Bush, then co-founded the Command Group with other former Bush officials in 2009. One of its businesses, CT Strategies, “supports the mission of federal clients, most notably U.S. Customs and Border Protection and other Department of Homeland Security agencies,” according to its site.

Federal records show CT Strategies has also secured contracts of its own, including a $6 million award in July to provide "professional, scientific and administrative services" to the government.

The Campaign Legal Center, a watchdog group founded by former Federal Election Commission member and Republican presidential campaign adviser Trevor Potter, filed an ethics complaint against Nielsen this week, citing the possibility of a financial windfall for Bingel. The complaint was sent to the White House, the Justice Department and the Office of Government Ethics.

“The consultant has clear financial incentive to assist in the nomination of an agency secretary who would have the power to steer government contracts in his direction,” said Larry Noble, the group’s general counsel, referring to Bingel.

“Government employees aren’t permitted to receive gifts or free services — especially from people with business before their department — because it calls the integrity of government decision-making into question,” Noble said. “This unusual arrangement should be investigated because of the clear potential conflict of interest, and the danger that Nielsen can be compromised as DHS secretary.”

The Campaign Legal Center said it has not received a response to its complaint.

With an annual budget of $44 billion, DHS pays thousands of federal contractors to provide goods and services that range from sophisticated technology to basic law enforcement gear. Companies vying for the largest awards often turn to consulting firms who employ former government officials with the contacts and inside knowledge to help them get an edge.

A current administration official said Nielsen is the only recent nominee at DHS who has relied on a private consultant as a sherpa.

Kevin McAleenan, the nominee to lead U.S. Customs and Border Patrol, had DHS legislative affairs staffers performing that role, the official said. So did David Pekoske, who was sworn in to lead the Transportation Security Administration in August. It was the same with Claire Grady, the DHS undersecretary for management.

Emilio Gonzalez, the former director of U.S. Citizenship and Immigration Services, a DHS agency, said it’s typically an advantage for a nominee to have current government officials steering them toward a successful outcome.

“You want people who are intimately aware of what’s going on in the department, who can bring you up to date on whatever is pressing at the time and will run interference by doing intel work on the Hill, such as which senator will be supportive and why,” said Gonzalez, who worked under both Bush administrations and now runs Miami’s international airport.

Bingel’s relationship to Nielsen did not come up during her Nov. 8 confirmation hearing. On Tuesday the panel voted 11 to 4 to advance her nomination, setting the stage for a full Senate vote.

The panel's vote was postponed twice, and a group of Democratic members wanted to bring Nielsen back for additional testimony after The Washington Post described White House attempts to pressure the acting director of DHS, Elaine Duke, over an immigration decision.

The White House is eager for Nielsen to be confirmed before Thanksgiving, according to Senate staffers.

Current administration officials said they are concerned that Bingel’s role in guiding Nielsen could set a precedent for future nominees, with lobbyists usurping the role of federal employees despite the potential conflicts of interests that will create.

Julie Tate contributed to this report.