Divided Government?

One of the desperate ploys that McCain has been using as of late is raising the specter of undivided Democratic control of Washington. He seems to be saying, you can let the donkeys have Congress, but don't let them have the Presidency too. Would this really work? If I support the Democratic Congress and their agenda, why would I want President McCain vetoing the bill the Democrats pass? Divided government comes from non-ideological, "personality" voters. People who like McCain, think he's mavericky, but also like their local Democratic congressman. Nobody thinks "I want the Democrats in office, but I wouldn't want them to actually do anything.