On the eve of the 2008 presidential election, a growing number of Californians are registering as “decline to state” voters at the expense of both major political parties.

Secretary of State Debra Bowen reports that the percentage of decline to state voters is 19 percent compared to 16 percent in September 2003, the fall tall prior to the 2004 election between GOP President George W. Bush and Democratic Sen. John Kerry of Massachusetts. (Download press release here.)

Democrats’ percentage fell from 43.6 percent to 42.5, while the GOP’s share dropped from 35.3 percent to 33.8 percent.

Theories abound as to why voters are increasingly disinterested in affiliating with traditional political parties.

And no one seems to agree on the best means by which to reverse the trend, either. Leaders of both parties engage in a near constant tug-of-war over their platforms and strategies between the ends of their internal political spectrums.

Some view the shift as a signal that voters are ready for a comparable third party but so far, there’s been little indication that this group of independent-minded people is interested in banding together.

There’s an even bigger problem on the political dance floor than the party shuffle, though.

New registrations since 2003 have not kept pace with population growth in California, resulting in a drop from 71 percent to 68 percent in the rate of eligible residents who register to vote. That means fewer people are making decisions at the ballot box that impact everyone.