On some issues, I am sure they are, judging by their Senate activities.
On the Viet Nam war -- I have never ceased to be amazed at how McCain and Kerry buddied up, once McCain got elected to the Senate, considering Kerry's anti-war activities that increased McCain's suffering in Viet Nam.
John McCain has always appeared to me to be mentally unstable as well as in his character and I do not trust him as a dog catcher, let alone a Senator. Kerry -- well, even more so.
How deep their collusion goes, I don't know. What makes so many Americans find McCain a likable pol, someone who could be trusted to lead, to make decisions for our good as a nation, is beyond me. He scares the stuffing out of me.
It goes deep enough that in the early 1990's, when "our" government was frantic to "normalize relations" with Vietnam so their corporate sponsors could start making buckets of money in the new market, there was a stumbling block to their plans - the vast amount of credible evidence that some American POW's and MIA's were still alive and being held by the Vietnamese, and the public efforts of their families and others to address this as a condition of recognition of Vietnam.
McCain and Kerry joined forces to harass, denigrate, sabotage and discredit the MIA families' investigations (Kerry's staff even shredded crucial documents).
In 2004 Kerry was derailed by the Swiftvets - in 2008 McCain's nemesis will be the POW/MIA families.
Doubtful that many Americans find McCain an acceptable candidate. His reputation is totally concocted by the media because he attacks the republicans at every turn.