We’ll know in a little more than a month just what this year’s election looks like on a Republican/Democratic scale. But aside from polls (which for the last few years we’ve generally gotten more skeptical of), are there other measures of party loyalty, and possible shifts? Unlike Washington and Idaho, Oregon has party registration.

What follow are a few numbers charting some of this, focusing on party registration numbers from August this year and the same month in 2008 and in the last break-even year in Oregon for Republicans, 2002. What we’ve worked out here is the percentage each group has within the total number of registered voters.

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Between the two major parties, you see here an uptick for Democrats from around 39% early in the decade, to 43% in 2008; and among Republicans, a loss from around 36% early in the decade to between 32% and 33% toward decade’s end. Where did the Democratic good fortune in the latter part of the decade come from? That swing of about 7-8% in registration is probably enough to account for a lot of it.

What about this year? As of August, compared with two years ago, registered Democrats account for a little less of the electorate (2.1% compared with 43.2%) than they did in 2008. There’s been some softening, but their position isn’t drastically changed: They are still well above where they were as recently as 2006.

And the Republicans? Their share of the overall voter universe has declined too, albeit very slightly, to within a tenth of a percentage point. They’ve lost less but still not gained anything. (The one area with gains has continued to be the Independent Party.)

Does this break down similarly around the state? Generally, it seems to.

Look at Washington County (Oregon’s second-largest), which has accounted more than any other one place in the state for the political changes over the last decade. In August 2010, the Democratic/Republican percentages were 41%/32.1%; in August 2008, they were 41.5%/33.2% (actually a little better for Republicans in 2008 than now). In 2002, the last close statewide D/R year, those numbers were 35.5%/39.3% – a substantial Republican registration lead.

In Clackamas County, the August 2010 D/R break was 40%/35.5%, and in 2008 41%/35.9% – drops for both parties, only a little greater among the Democrats. In 2002, the comparable was 37.7%/38.7%.

Multnomah County has long been Democratic, but the overall 2002 registration percentage for Democrats was just 48.7%. In 2008 it rose to 57.2%, and in August was 56.3%.

So on it goes, county after county (at least among the larger ones).

Of course, there’s the possibility than the softening in numbers in 2010 could be the start of another trend. We’ll know more about that in another couple of years. For now, the Oregon electorate looks structurally a lot like that of 2006 or 2008. Of course, whether the winners and losers reflect that depends a lot on who gets out to vote.