A proposal redrawing state Senate and state House districts will be revealed this afternoon, with changes in store for the House districts in Dorchester and Mattapan.

Due to population shifts across the state, a special legislative committee has been charged with redrawing the boundaries of Senate, House and Congressional districts.

Each Senate district must have 163,691 residents, and each House district must hold 40,923 residents.

The State House News Service reported in August that four members of the Dorchester delegation need huge population increases. They include state Reps. Marty Walsh, Linda Dorcena Forry, Carlos Henriquez and Russell Holmes.

The press conference unveiling the proposal is set for 2 p.m. at the State House.

Congressional maps will be released later this year, and speculation has largely centered around a scenario that has Congressman Stephen Lynch and Bill Keating facing off in a new district. Massachusetts is losing one of its 10 Congressional seats because of the aforementioned population shifts. Each one of the nine Congressional seats will have to hold 727,514 residents.