North Carolina Association of Teen Democrats

Jennifer Steinhauer, The New York Times

Well before Sens. Barack Obama and John McCain rose to the top of their parties, a partisan shift was under way at the local and state level. For more than three years starting in 2005, there has been a reduction in the number of voters who register with the Republican Party and a rise among voters who affiliate with Democrats and, almost as often, with no party at all.

Though the implications of the changing landscape for Obama and McCain are far from clear, the registration numbers may signal the beginning of a move away from Republicans that could affect local, state and national politics over several election cycles. Already, there has been a sharp reversal for Republicans in statehouses and governors' mansions.

In several states, including the traditional swing states of Nevada and Iowa, Democrats have surprised their own party officials with significant registration gains. In both of those states, there are now more registered Democrats than Republicans, a flip from 2004. No states have switched to the Republicans over the same period, according to data from 26 of the 29 states in which voters register by party. (Three of the states did not have complete data.)

In six states, including Pennsylvania, New Hampshire and Iowa, the Democratic piece of the registration pie grew more than 3 percent, while the Republicans' share declined. In only three states -- Kentucky, Louisiana and Oklahoma -- did Republican registration rise while Democratic registration fell, but the Republican increase was less than 1 percent in Kentucky and Oklahoma. Louisiana was the only state to register a gain of more than 1 percent for Republicans as Demo-cratic numbers declined.

Over the same period, the share of the electorate that registers as independent has grown at a faster rate than Republicans or Democrats in 12 states. The rise has been so significant that in states like Arizona, North Carolina and Colorado, nonpartisan voters essentially constitute a third party.

Holding steady

Swings in party registration are not uncommon from one year to the next, or even over two years. Registration, moreover, often has no impact on how people actually vote, and people sometimes switch registration to vote in a primary, then flip again come Election Day.

But for a shift away from one party to sustain itself for so long -- the current registration trend is now in its fourth year -- is remarkable, researchers who study voting patterns say. And though comparable data are not available for the 21 states where voters do not register by party, there is evidence that an increasing number of voters in those states are also moving away from the Republican Party based on the results of recent state and congressional elections.

"This is very suggestive that there is a fundamental change going on in the electorate," said Michael P. McDonald, a senior fellow at the Brookings Institution and an associate professor of political science at George Mason University who has studied voting patterns. He added that, more typically, voting and registration patterns tend to even out or revert to the opposing party between elections.

Doesn't look good

Dick Armey, the former House majority leader and one of the designers of the so-called Republican Revolution of 1994, said: "Obviously, these are not good numbers for the party to be looking at."

But in terms of the presidential election, Armey said the tea leaves are harder to read.

"I think the key in this one is, where do all these new independent voters break?" he said. "I think right now, you've got a guy in western Pennsylvania saying, 'I am really disgusted right now, and I'm not going to register as a Republican anymore, but I really don't want this guy Obama elected."'

Those in charge of state Democratic parties cite a national displeasure with the Bush administration as an impetus for the changing numbers, which run counter to a goal of Karl Rove, President Bush's former top adviser, to create a permanent realignment in favor of Republicans.

"I think nationally and here, people are kind of tired of the way this administration has been conducting the policies of this country," said Pat Waak, chairwoman of the Colorado Democratic Party.

Yet though an unpopular war, a faltering economy and a president held in low esteem have certainly combined to hurt the Republican Party, Democrats are also benefiting from demographic changes. They include the rise in the number of younger voters and the urbanization of suburbs, which has resulted in a different political flavor there. The party has also been helped by a recent willingness to run more pragmatic candidates, who have helped make the party appeal to more voters.

REGISTRATION DATA: Among the 26 states with registration data, the share who have signed on with Democrats has risen in 15 states since 2004, and rose among Republicans in six states, according to state data. The number of registered Democrats fell in 11 states, compared with 20 states where Republican registration numbers fell. In the 26 states and the District of Columbia where registration data were available, the total number of registered Democrats increased by 214,656, while the number of Republicans fell by 1,407,971.