This is a bad idea.

IS Sen. John McCain going to quit the Republican Party and become the running mate of Sen. John Kerry in the 2004 presidential race?

Don't be fooled simply because McCain portrays himself as a GOP rebel, lone champion of campaign finance reform and the environment. He's a dyed-in-the-wool conservative.
I was pretty sold on Kerry too. Oh well. Hopefully this is just a rumor. It's troubling though. Have we become so preoccupied with beating the Bushies that we're willing to sell out completely?