Redistricting will cost House Minority Whip Steny H. Hoyer (D) the most constituents of any Maryland lawmaker, and Rep. Elijah E. Cummings (D) will have to gain the most, according to data released Wednesday by a panel tasked with rebalancing population in the state’s congressional districts.

The population in Hoyer’s 5th district in southern Maryland has grown by almost 47,000, or more than twice as much as that of any other Maryland House member since the 2000 Census.

The shift reflects strong population growth in Washington’s Maryland suburbs, including a substantial increase in the numbers of minorities. Charles County, which sits entirely in Hoyer’s district, is now 52 percent minority, up from 32.7 percent in 2000.

By contrast, the shrinking population in Cummings’s 7th district, which has lost more than 57,000 residents, highlights the loss of tens of thousands of residents in Baltimore over the past decade.

Maryland’s meandering northern 2nd district, represented by C.A. “Dutch” Ruppersberger, the ranking Democrat on the House Intelligence Committee, will also have to be significantly redrawn. His district lost 17,700 residents, the second most of any Maryland House member.

Freshmen Republican Rep. Andy Harris, of Maryland’s 1st District on the Eastern Shore, also will face efforts by the state’s powerful Democrats to reshape his district. It gained 21,500 residents, or the second most of any Maryland congressman.

Jeannie D. Hitchcock, newly elected chairman of Gov. Martin O’Malley’s redistricting advisory commission, promised Wednesday to conduct a “fair and open” process redrawing the state’s legislative districts, saying the board would meet at several places across the state between now and September to take public input.

The commission, made up of mostly Democrats, must make its recommendations to O’Malley before he calls the General Assembly into a special session in October to approve the new boundaries. Each Maryland congressional district should have about 721,529 residents.

The Maryland Republican Party released its own proposed map Tuesday night. The party called for keeping boundaries more consistent with county lines, which would eliminate the way several House members now get a piece of Baltimore’s reliably Democratic constituency.

“For 10 years we have lived with some of the worst gerrymandered congressional districts in the country, purely because one political party chose to put their electoral interests over what’s best for Maryland voters,” said Maryland GOP Chairman Alex X. Mooney. “This cannot continue.”

O’Malley’s administration says it will post instructions soon on its Web site for how members of the public can propose their own maps.