The Edwards-Clinton Mutual Sustainability Pact

John Edwards remains strong in Iowa, per a new Time Magazine poll.

John Edwards and Hillary Clinton have a mutual interest in seeing each other's candidacy prosper over the next four months.

Edwards wants Clinton's national poll ratings to rise, rise, rise. That way, if/when he beats her in Iowa, he will have slain a giant. Also, the thinking in Edwards land is that if Clinton rises, the press will conclude that Barack Obama is falling.

Clinton wants Edwards to keep his lead in Iowa and remain competitive nationally. Some of her advisers figure that Edwards and Obama are competing for largely overlapping pool of undecided voters.

Edwards also fires at Obama from his left and provides voters with a nice contrast, in the minds of the Clinton campaign, in terms of policy. It's probably true that some Clinton advisers are comfortable, right now, with John Edwards's being seen as the boldest candidate, policy-wise. Better Edwards than Obama.

Defeating Edwards in Iowa -- something the Clinton campaign believes is doable but not absolutely vital -- could clinch the nomination for Clinton if and only if Edwards remains strong enough to be...beaten.