Nearly a year after the Federal Transit Administration began withholding millions from Maryland, Virginia and the District for their failure to launch an independent Metro safety oversight group by a February 2017 deadline, the process has been slowed by key vacancies, the search for an executive director and the process of seeking final federal approval for the long-awaited safety panel.

Regional leaders aimed to establish the Metro Safety Commission by the end of 2017 but have been held up by the search for an executive director and the need to seat commissioners to the six-member panel. The FTA has now withheld $15.8 million from the District, Maryland and Virginia for their failure to establish the safety group, an agency spokeswoman said, up from $8.9 million in July.

Virginia and Maryland have appointed their commissioners to the body, but D.C. Mayor Muriel E. Bowser (D) and the D.C. Council had yet to announce selections to the panel by Thursday.

Thursday afternoon, however, Bowser spokeswoman LaToya Foster said the mayor had appointed Robert Bobb as a voting director and Christopher Geldart as an alternate to the commission. Bobb is a former D.C. city administrator who served as emergency financial manager for Detroit Public Schools; Geldart is a former director of D.C.’s Homeland Security and Emergency Management Agency.

With authorizing legislation enacted at the federal, state and D.C. levels, the safety commission is now in the final stage of federal approval before certification. But with critical tasks remaining — the appointment of an executive director, the hiring of inspectors and the federal handoff of critical oversight tasks — Virginia Transportation Secretary Aubrey Layne said Thursday that a “realistic” timeline for the panel’s launch is an additional six months.

“It’s taken a lot longer than we anticipated with our partners getting together their personnel, but it is what it is,” he said. “It’s similar to [Metro]. It’s dealing with different regional issues and the politics of doing that.”

The FTA said it will continue to withhold funding from the region until the oversight group is certified, potentially squeezing budgets for transit agencies as far away as Virginia’s Hampton Roads region. Before the handoff can take place, the FTA said in a statement, the safety commission must demonstrate to federal officials that it can handle the safety monitoring the federal government assumed in October 2015, when then-U.S. Transportation Secretary Anthony Foxx took the unprecedented step of placing Metro under FTA oversight.

“Upon successful completion of the transition, FTA will certify the MSC’s [state safety oversight] program and relinquish federal safety oversight of Metrorail,” the FTA said in a statement. The agency mandated that 30 states establish safety oversight panels for transit systems by 2019, but Metro’s urgent safety needs prompted earlier deadlines from the federal officials.

A spokeswoman for D.C. Council Chairman Phil Mendelson (D) said the council hopes to make its nomination to the commission by February. Founding legislation in D.C. enabled the mayor and Council to each make appointments to the six-member safety body, which has an additional three alternates — one representing each jurisdiction.

Layne and Maryland Del. Marc A. Korman (D-Montgomery) stressed the urgency of the District’s appointments, noting that an executive director cannot be hired until all six commissioners are in place. A Metropolitan Washington Council of Governments spokesman said that the panel hired a search firm to assist the jurisdictions in finding a candidate but that the commissioners themselves will interview and select the director. The COG expects the executive director to be hired in the first quarter of the year, the spokesman said.

The commissioners appointed thus far are a mix of safety experts and former transit agency employees with management experience.

Virginia’s appointees are former American Public Transportation Association vice president Greg Hull and former National Transportation Safety Board chairman Mark V. Rosenker. The state has not announced an alternate. Maryland’s commissioners are Howard H. Roberts, former New York City Transit president, and Debra A. Farrar-Dyke, a former Metro liaison for disadvantaged business enterprises who now serves on the Maryland Transportation Commission. The state also appointed John Contestabile, program manager for homeland security for Johns Hopkins University’s applied physics lab, as an alternate.

The panel will replace the regional body that predated federal oversight, the Tri-State Oversight Committee, which was criticized as toothless and under-resourced in the wake of the 2009 Red Line crash that killed nine, including a train operator, near Fort Totten and the 2015 L’Enfant Plaza smoke calamity that led to the death of 61-year-old Carol Glover.

Korman said the region is making progress on the safety panel, noting it was difficult to anticipate how long the first-of-its-kind process would take. “It feels like it’s taking longer than it needs to, but it is complicated, it is multi-jurisdictional,” said Korman, co-chair of a work group in Annapolis focused on Metro issues. “It’s not just check the box so we can get the money, but also we want them to provide useful and rigorous oversight.”

U.S. Transportation Secretary Elaine Chao made the decision to withhold 5 percent of a key funding category because the District, Maryland and Virginia officials missed the Feb. 9, 2017, deadline to prop up the oversight group.

Local congressional leaders argued the FTA’s deadline, set before they were provided a “tool kit” providing guidance on how to achieve certification, set the region up for failure.

In a June 30 letter to Chao, 11 Democratic lawmakers, including Rep. Gerald E. Connolly and Sens. Tim Kaine and Mark R. Warner, all of Virginia, said that “the decision to withhold the funds . . . was crude, punitive, and arbitrary.”

A separate letter from six members of Congress, including Kaine, Warner and Rep. Barbara Comstock (R-Va.), argued the FTA gave the jurisdictions “a deadline so unrealistic that failure was unavoidable.”

Six months later, with the commission still not in place, Layne, the transportation secretary, withheld criticism of the federal position.

“Whether it’s fair or not, it is where we are right now,” he said. “I suspect they believe it’s their only leverage that they have left in this. . . . I would have taken a different approach. But on the other hand here we are, still not having it ready as a region.”