At the time, Massachusetts elected United States Senators by a majority vote of the combined houses of the Massachusetts General Court.
- Eben Sumner Draper, former Governor of Massachusetts
- Curtis Guild Jr., U.S. Ambassador to Russia and former Governor of Massachusetts
- George P. Lawrence, U.S. Representative from North Adams
- Robert Luce, Lieutenant Governor of Massachusetts
- Samuel Walker McCall, U.S. Representative from Winchester
- John Wingate Weeks, U.S. Representative and former Mayor of Newton
|Republican||John W. Weeks||97||60.25%|
|Republican||Samuel Walker McCall||57||35.40%|
|Republican||Curtis Guild Jr.||5||3.11%|
|Republican||George P. Lawrence||1||0.62%|
After winning the caucus nomination on the thirty-first ballot, Weeks's support was made unanimous by acclamation on a motion by McCall supporter Claude L. Allen. The motion was seconded by Guild supporter John L. Sherburne.
|Republican||John W. Weeks||26||66.67%|
|Democratic||Sherman L. Whipple||11||28.21%|
|Democratic||John A. Keliher||1||2.56%|
|Democratic||Joseph C. Pelletier||1||2.56%|
|Republican||John W. Weeks||134||57.51%|
|Democratic||Sherman L. Whipple||69||29.61%|
|Progressive||John Graham Brooks||5||2.15%|
|Democratic||John F. Meaney||3||1.29%|
|Democratic||James B. Carroll||3||1.29%|
|Democratic||Charles A. DeCourey||3||1.29%|
|Democratic||Charles Sumner Hamlin||2||0.86%|
|Democratic||John A. Thayer||2||0.86%|
|Democratic||John F. Fitzgerald||2||0.86%|
|Republican||Curtis Guild Jr.||1||0.43%|
|Democratic||Philip J. O'Connell||1||0.43%|
|Democratic||Richard Olney II||1||0.43%|
|Democratic||Joseph Henry O'Neil||1||0.43%|
|Democratic||Andrew J. Peters||1||0.43%|
|Democratic||Harvey H. Pratt||1||0.43%|
|Socialist||Roland D. Sawyer||1||0.43%|
|Democratic||John P. Sweeney||1||0.43%|
|Democratic||George Fred Williams||1||0.43%|
- 26 Senate votes, 134 House votes
- 11 Senate votes, 69 House votes
- "REPUBLICANS READY TO ELECT MR. WEEKS BAY STATE SENATOR". The Christian Science Monitor. January 14, 1913. p. 1.
- "Our Campaigns - MA US Senate Race - Jan 14, 1913".
- "United States Senators Chosen, 1912". The Tribune Almanac and Political Register 1913. New York: The Tribune Association. 1913. p. 457 – via Hathi Trust Digital Library.