Arguably Maryland's most influential lawmaker is set to lose the most constituents through redistricting, as Maryland Gov. Martin O'Malley's administration plans for the politically paramount redrawing of congressional districts this fall.

Based on population shifts recorded in the census, Democratic House Minority Whip Steny Hoyer's district will shrink the most, and fellow Democratic Rep. Elijah Cummings, of Baltimore, will gain the most constituents. Each congressional district is required to have 721,529 residents.

Populations have grown in nearly every Maryland jurisdiction, with Montgomery and Prince George's counties gaining the most residents over the past decade. Hoyer's 5th Congressional District contains more than 768,000 residents from Southern Maryland and a portion of Prince George's County.

In comparison, Baltimore lost roughly 30,000 residents over the last 10 years, which will lead to the expansion of Cummings' district.

The General Assembly will convene a special session in October to redraw the state's congressional districts, and will redraw state legislative districts in January.

Maryland Republicans are already calling for a dramatic changing of the lines, which they say allow multiple Democratic House members to pilfer support from the liberal Baltimore area.

"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 Republican Party Chairman Alex Mooney. "This cannot continue."

A heavily Democratic committee appointed by O'Malley will make recommendations to the governor before the special session.

Included among the group are Senate President Thomas V. Mike Miller Jr., House Speaker Michael Busch and longtime O'Malley aide Jeanne Hitchcock. The lone Republican on the panel is former Del. James King of Anne Arundel County. Richard Stewart, a Prince George's resident and member of O'Malley's transition team, fills the citizen post on the five-member commission.

The legislative redistricting panel will hold 12 public hearings across the state in coming months, O'Malley's office announced.