From a 2000 NYT article:
In the end, Mr. McCain decided not to run for Congress in 1976, but after Jacksonville he got an assignment that put him in the center of the political world anyway: he was appointed Navy liaison to the Senate. Normally, the liaison officers are glorified travel agents for senators making overseas trips — “baggage carriers,” they are snidely called — but Mr. McCain’s personality and renown as a war hero made his cramped office a magnet for key senators.
“He was a fascinating character,” recalled Gary Hart, then a liberal young senator who often dropped by Mr. McCain’s office. “He was current on the issues and could engage on every level. And he was very funny.”
One of the attractions for some liberals was that Mr. McCain held no grudge against the antiwar movement. William B. Bader, then a Senate committee staff member, remembers sitting next to Mr. McCain on an airplane as they accompanied a delegation of senators on an overseas trip.
“One senator after another came back to talk to John,” Mr. Bader said. “The senators who came back were the biggest doves, and I think psychologically they wanted to make their peace with the war.”
Mr. McCain became particularly close to William S. Cohen, then a senator from Maine, John Tower, then a senator from Texas, and Mr. Hart.
http://partners.nytimes.com/library/politics/camp/022700wh-gop-mccain.html
Even before he was a “foot soldier for the Reagan Revolution” he was a friend of the liberals.
That line is getting so tired and old...kinda like he is.