Supporters of the late Sen. Edward M. Kennedy, D-Mass., have vowed to pack a public hearing on Wednesday to press Massachusetts lawmakers to allow the governor to name an interim replacement to his vacant U.S. Senate seat.
Critics say they will not let the proposal go unchallenged.
They have called it a political power grab by Democrats to ensure there are enough Senate votes to pass President Barack Obama's health care overhaul plan.
Before his death last month from brain cancer, Kennedy sent a letter to Gov. Patrick Deval asking lawmakers to change state law to allow an interim Senate appointment to serve until a special election could be held.
Organizers on both sides have urged people to turn out in force at Wednesday's hearing.