The Republican Debate and the Mad Dash to Tsunami Tuesday

John McCain went into last night's debate as the Republican front-runner against Mitt Romney, with Mike Huckabee and Ron Paul standing by. Before tonight's Democratic debate, Hillary Clinton's lead over Barack Obama appears to be slipping. McCain and Romney are competing to lead a party now sharply divided between moderates and conservatives. Are Obama and Clinton different enough to expose gulfs between Democrats? Will this week's debates make a difference? What's at stake next week when Super Tuesday creates the equivalent of national campaigns for both parties?

• Correction: We quoted Bill Clinton as saying in a speech, "We just have to slow down our economy and cut back our greenhouse gas emissions ‘cause we have to save the planet for our grandchildren." Although he did say that, he went on to explain at length why slowing down the economy would not be a good idea. Warren, who did not know the full context, apologizes and thanks listeners for pointing out his mistake.