The preamble part of Tom Lehrer’s song George Murphy:
It was from his That Was The Year That Was, which came out in 1965… so it’s likely not a dig at JFK… what was going on in Massachusetts at the time that this references?
Robert Kennedy, who had strong ties with Massachusetts, had been elected as New York’s Senator in 1964.
Ahhhh okay. So he’s saying they have the two regular senators plus a de facto third in Bobby Kennedy b/c Kennedy was repping NY even though everyone knew he was a Mass guy. Makes sense 
Didn’t Bobby Kennedy grow up in New York State, though?
Ted Kennedy joined the Senate in 1962 after a special election to fill the seat left by JFK. He won a full term in 1964.
Partly. Robert Kennedy was born in Massachusetts. During his childhood, the Kennedy family had a residence in both New York and Massachusetts. Robert went to private schools in New York, New Hampshire, and Massachusetts. He went to college in Massachusetts and Virginia. After graduating, he worked in Washington, Boston, and New York City. So he had legitimate claims to calling New York his home state but it was an issue in his Senate run.
The Kennedy family lived in Riverdale, in the Bronx, and Bronxdale, in Westchester County, from 1927 (when Bobby was about 2) until 1938, when Joe Sr. was appointed Ambassador to the UK. They spent summers in Massachusetts. After that Bobby attended schools in New Hampshire, Rhode Island, and Massachusetts.
Initially RFK was angling for the Vice Presidential nomination under Johnson, but the two men hated each other, and at the end of July LBJ announced he wouldn’t select any sitting cabinet member as his VP. This excluded RFK, who was still Attorney General.
At the time he was a resident of Virginia, but couldn’t run there because Harry Byrd had a grip on politics in the state. He couldn’t run in Massachusetts because his brother had just been elected senator.
He didn’t announce his run for the Senate from New York until August 1964 and had to scramble to establish residency. In fact, he was only renting before the election.
After Johnson’s announcement that he would not select any cabinet member Bobby was quoted as saying that he was sorry he took so many good men down with him.