The 'beef' is that there isn't a candidate representing Republican values. Anybody who votes for McCain deserves what they get. George Bush only (and barely) won re-election in 2004 because we were otherwise threatened with a Kerry presidency. Still the Republican party hasn't gotten the message. Apparently they still think the politics of blackmail will work one more time. I don't think it will. During the 2004 election, the chairman of the Republican party arrogantly mocked my criticism of the big spending big goverment ways of the Bush administration. He said "what are you going to do, vote for Kerry? You have nowhere else to go". Well, people who don't have anywhere to go just stay home, don't they? And without us so-called 'disaffected' (I prefer to call us abandoned) former Republicans, the GOP has little hope of retaining the Whitehouse.
So, if they want to run McCain, go ahead. After 8 years of Bush, we can survive anything, even a Hillary/Obama presidency.