Maryland doctors and health care activists are planning to start a battle in Annapolis on Thursday against U.S. House Republicans' efforts to repeal federal health care reform.

Maryland Health Secretary Josh Sharfstein is headlining the list of speakers for the event, which is scheduled the day after the House is expected to vote on a repeal of the Affordable Care Act.

Obama officials say as many as 2.5 million Marylanders could lose health care coverage if the repeal is passed, according to a report released Tuesday by the U.S. Department of Health and Human Services.

Maryland Gov. Martin O'Malley joined U.S. Health Secretary Kathleen Sebelius and Delaware Gov. Jack Markell on Tuesday to discuss the local impacts of a repeal with reporters over a conference call.

"From 2003 to 2009, employer-sponsored premiums rose 50 percent," O'Malley said. "There is no way our businesses can expand if we are watching health care costs rise by 50 percent and wages stay stagnant."

He said Maryland plans to begin implementing health care reforms as soon as possible. 

"Maryland is looking forward to being one of those early implementers," he said.

Some health care officials warn that the state doesn't have the capacity to implement many reforms, however.