The state’s top health-care regulator is stepping down effective Jan. 7.

Justin Senior, the secretary of the Florida Agency for Health Care Administration, sent an email to his staff Tuesday afternoon saying he will leave the agency to pursue an “outside opportunity.” The Safety Net Hospital Alliance of Florida announced late Tuesday that Senior will become the group’s chief executive officer.

“I do not have words to describe how much I have enjoyed working at AHCA and with all of you — it just has been an incredible experience and one that I will always deeply appreciate,” he wrote in the email to AHCA’s staff. “The work that you do positively impacts the lives of millions of Floridians and I have had the good fortune and opportunity to work with some of the smartest, nicest and most dedicated people in the country on a daily basis.”

Senior had been seen as a potential agency head who might remain after the transition from the administration of Gov. Rick Scott to the new administration of Republican Gov.-elect Ron DeSantis. AHCA houses the state’s Medicaid program but also is charged with regulating health-care facilities such as hospitals and nursing homes.

Congressman Matt Gaetz, who is part of the DeSantis transition team, said no decision has been finalized on who will replace Senior. He said the transition team has conducted interviews, but it is “not close to an announcement on anyone.”

Senior, whose resignation is effective the day before DeSantis is inaugurated, has been the head of AHCA since October 2016, when he took over for veteran state official Liz Dudek. Before he moved into the top job at the agency, he was Florida’s Medicaid director for five years. Prior to that, he worked in the agency’s general counsel’s office.

In his new role at the Safety Net Hospital Alliance of Florida, Senior will serve as the organization’s CEO, while Lindy Kennedy will assume the title of president and chief operating officer, according to the announcement from the group. Kennedy became president this year following the retirement of long-time leader Tony Carvalho.

Senior will start the position in January.

“I am honored and excited to be a part of an organization whose hospital members are beacons in their communities, providing vital services that benefit those who need them most,’’ Senior said in a statement issued by the group. “I look forward to ensuring our hospitals have the resources and attention they need to ensure all Floridians have access to affordable, high-quality health care.’’

Senior will be precluded from lobbying AHCA but will not be banned from lobbying lawmakers. The alliance lobbies on behalf of 14 hospital and health systems across the state, including public, children’s and teaching hospitals that treat some of the poorest patients. Combined, the hospitals provide nearly 50 percent of all Medicaid hospital care.

At AHCA, Senior advocated for steep reductions in the amount of Medicaid payments to safety-net hospitals. While hospitals complained about the reductions, Senior, echoing his boss, Scott, repeatedly told lawmakers that hospitals made money.

Senior also helped oversee the state’s transformation of its massive Medicaid program from a fee-for-service program to one that now enrolls most patients in privately-run health maintenance organizations.