During the month of March, 37.2% of American adults considered themselves to be Democrats while just 31.5% considered themselves Republicans. Those numbers are little changed from last month, but confirm a significant movement away from identification the Republican Party. March was the sixth consecutive month (and seventh month out of eight) that the Democrats have enjoyed a net advantage of at least five points (see history). Prior to this recent stretch, the Democrats had never enjoyed a five-point advantage in the data released by Rasmussen Reports (a period of 31-months).

One year ago, in March of 2006, the Democrats enjoyed a net advantage less than half as big as in 2007. These results are based upon tracking surveys of 15,000 adults per month. The margin of sampling error is less than one percentage point, with a 95% level of confidence. Please keep in mind that figures reported in this article are for all adults, not Likely Voters.

Another significant note is that 31.3% of Americans now refuse to identify with either major party. That’s a seven percentage point increase since Election 2004 and the highest total of unaffiliateds ever measured. Most of the growth in unaffiliateds has come from the GOP. The number of Democrats in the adult population has remained more stable over the past 3 years.

Still, just 20% of voters give Congress good or excellent marks. That’s a big improvement from 11% when the GOP was last in charge, but hardly a ringing endorsement of the current crop of legislators in the nation’s capitol.

Monthly data from January 2004 to February 2007 can be reviewed here.