Party Affiliation Trends highlight the difference between Election 2006 and Election 2004.

In September 2004, as the nation prepared to re-elect George W. Bush and a Republican majority in Congress, the GOP had pulled just about even with Democrats in terms of party affiliation. At that time, 37.9% of Americans considered themselves Democrats while 37.3% considered themselves Republicans. That was the GOP’s best performance of 2004 and reflected a net gain of three percentage points in six months.

This time around, the trends are heading in the opposite direction. During September 2006, 37.0% consider themselves Democrats and just 32.2% identify with the GOP. That’s a net advantage of 4.8 percentage points for the Democrats and presents a much different political environment from the last election cycle. Not only that, this time around, it’s the Democrats who are gaining ground. They’ve gained a net three percentage points since the beginning of 2006.

Overall, the number of Democrats is similar to 2004, but the number of Republicans has declined significantly. Today, 30.7% are not affiliated with either major party. That’s up from 24.8% two years ago.

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.

As the party affiliation trends continue moving in the Democrats’ direction, the battle for control of the Senate keeps getting closer. Our October 2 update of the Senate Balance of Power summary shows both Republicans and Democrats with 49 seats in their column. A month ago, the Republicans looked ready to emerge from Election 2006 with 50 seats to 47 for the Democrats.

The President’s Job Approval ratings continue to hover around the 40% mark and voters everywhere believe the political system is badly broken.

Please keep in mind that figures reported in this article are for all adults, not Likely Voters. Republicans typically do a bit better among Likely Voters (in fact, the two parties ended up even among those who showed up to vote in 2004).

Monthly data from January 2004 to September 2006 can be reviewed here.

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Scott Rasmussen, president of Rasmussen Reports, has been an independent pollster for more than a decade.