Obama has said he would meet unconditionally with dictators, though he subsequently qualified that pledge by saying there must be certain unspecified advance "preparations." Last year at the National Press Club in Washington, Biden criticized Obama's initial statement saying, "Would I make a blanket commitment to meet unconditionally with the leaders of these countries within the first year I was elected president? Absolutely, positively no."
Obama has said that Saddam Hussein "poses no imminent and direct threat to the United States, or to its neighbors." Biden thought otherwise: "This is a guy who's used weapons of mass destructions. This is a guy who has destabilized the whole neighborhood. This is a guy who in a war with Iranians, over 800,000 people on both sides were killed. This is a guy who is an extreme danger to the world. And this is a guy who is in every way possible seeking weapons of mass destruction. That case, in and of itself, ought to be sufficient." ("Meet the Press," Aug. 4, 2002)
The McCain campaign can revisit quotes other than those of Obama and Biden. It has produced a new ad featuring Hillary Clinton, which recalls some of her criticisms of Obama and "empathizes" with her for not being chosen by Obama as his running mate.
There's also the issue of Obama's much touted ability to reach out and compromise with Republicans. According to the National Journal, Obama has the Senate's most liberal voting record. Joe Biden was ranked third most liberal in 2007. No demonstration of compromise there.
Biden is not "change we can believe in." He is change to deceive with. Biden's toughest opponent is not John McCain and whoever he picks as his running mate. Biden's toughest opponent is himself.