WASHINGTON (PNN) - December 23, 2011 - More than 2.5 million voters have left the Democrat and Republican Parties since the 2008 elections, while the number of Independent voters continues to grow.

A USA Today analysis of state voter registration statistics shows registered Democrats declined in 25 of the 28 states that register voters by Party. Republicans dipped in 21 states, while Independents increased in 18 states.

The trend is acute in states that are key to next year's presidential race. In the eight swing states that register voters by Party, Democrats' registration is down by 800,000 and Republicans' by 350,000. Independents have gained 325,000.

The pattern continues a decades-long trend that has seen a diminution in the power of political parties, giving rise to independents like Ross Perot and Ralph Nader and the popularity this year of libertarian Republican Ron Paul.

"The strident voices of both the (political) left and right have soured people from saying willingly that they belong to one Party or the other," says Doug Lewis, who represents state elections officials. "If both sides call each other scurrilous dogs, then the public believes that both sides are probably scurrilous dogs."