State primaries are the only contests that really count for selecting a presidential nominee. The national population never weighs in, which notoriously means that people count for a lot more in New Hampshire than in, say, Maryland. Nevertheless, the candidates are surely interested in their standing among all Americans who register with their party. That’s partly because their level of national support will influence state primary voters. And it’s partly because the primary calendar is so compressed and unpredictable this year that it’s risky to rely on particular states.
Here, then, is a graph showing support for Senators Clinton, Obama, and Edwards among likely Democratic voters nationwide. (Source for the data.)
The three leading candidates have gained since January, at the expense of “don’t know/undecided.” Senator Clinton quickly rose to the mid-30-percent range and has then had very stable support. Support for Senators Edwards and Obama has been more volatile and has sometimes traded-off. For example, during the third week of March, Obama gained at Edwards’ expense, but then that trend reversed. It’s as if 35% of the Democratic electorate has settled on Senator Clinton, and the rest prefers an alternative–but hasn’t decided who that should be.