- Governor Endicott Peabody appoints Kennedy's former primary opponent, Edward J. McCormack, Jr., to the seat vacated in the light of Kennedy's death. McCormack goes on to win the general election held in Massachusetts in November of 1964, owing to both sympathy votes and to the liberal wave of President Johnson being re-elected.
- Important progressive legislation is either not passed or delayed without the legislative presence of Teddy Kennedy.
- The left-wing of the Democratic Party is probably considerably weaker without the leadership of Kennedy. Another, less prominent progressive Democrat becomes the public face of the Democratic left, though I honestly don't know who that might be (Fred Harris?).
- Senator McCormack serves out two terms, losing his spot to run for the Democratic Senate nomination in 1982 to Governor Michael Dukakis. Dukakis goes on to win the seat, serving in Congress until his defeat by Mitt Romney in 1994. Senator Romney serves from 1995 until 2007, losing in the Democratic wave that would propel Joseph Patrick Kennedy II to the Senate.