It's the oldest, worst, and most effective part of American politics: go negative. Voters say they hate it, but it works. There's no way to frame your opponent's weakness any better. Chris deconstructs history's hardest hits—and how they were so effective—with Andrea Mitchell, senior Washington correspondent for NBC News and host of "Andrea Mitchell Reports," and Mike Murphy, who's handled media and strategy for Republicans running for President, the US Senate, and governorships.