The Progressive Change Campaign Committee is pushing Massachusetts' governor to appoint retired Rep. Barney Frank (D-MA) as the state's interim senator to replace John Kerry.
Frank has said he wants the position when Kerry leaves to become secretary of state, for which he is expected to be easily confirmed.
The liberal advocacy group launched their campaign in an email to supporters and unveiled the website AppointBarneyFrank.com.
"As Elizabeth Warren takes a principled stand against cuts to Social Security, Medicare, and Medicaid benefits, we can't afford to have our other senator be lukewarm, undecided, or uncertain. We need someone who we are 100% confident will fight right alongside her. Barney Frank is that person," PCCC wrote in an email.