In 2008, when Democratic voter registration spiked in the traditional Republican stronghold of Montgomery County, GOP leaders attributed it to Obama-mania.

But five years later, in a primary season wanting for passion or drama, Montgomery County Democrats not only have maintained their registration edge, they have added to it.

Among major-party registrants, 54 percent are Democrats, compared with 52 percent for the 2008 presidential election. Democrats now constitute 46 percent of all voters in the county, compared with 45 percent in 2008.

The fresh figures affirm that the region's political landscape has shifted dramatically in the last decade. In Chester County, Democrats now claim 45.9 percent of the major-party registrations, compared with 35.6 percent in 2003. In Delaware County, the Democratic share is 49.9 percent, compared with 34.4 percent 10 years ago.

Meanwhile, in all five counties, the numbers of voters unaffiliated with either party has risen in the last decade - dramatically in Philadelphia, where that figure has jumped by more than 50 percent, according to final preprimary data from the Pennsylvania Department of State.

Still, Democrats have made gains in the city and now claim 87 percent of the major-party registrants. There were more than 40,000 fewer Republican voters this year than in 2003, with more than 115,000 additional Democratic voters registered.

In Montgomery and Bucks Counties, unaffiliated new registrants outnumbered Republicans.

Montgomery County Democratic Chairman Marcel Groen credited registration gains to what he called the party's moderate views on social issues, stable leadership, and strong candidates.

"I think we had a lot of people here who were closet Democrats, but who had always voted Republican for one reason or another," he said. "People just want logical approaches to the problems facing our country today."

Democratic registrations have been creeping upward since the late 1990s, Groen said. Last year, Democrats assumed control of the county's Board of Commissioners for the first time since 1881.

Pat Poprick, chair of the Bucks County Republican Committee, said she put little stock in the numbers. New voter registrations have often fluctuated in years past, she said, and new Republican registration numbers have been low even in years when the party has gone on to win local elections.

"The registrations are no more than something that gets marked down on a list," she said. "What matters is how people vote."

Poprick attributed the jump in unaffiliated voter registrations to two factors. Many new registered voters are young people, she said, some of whom consider themselves independent voters.

Others, she said, might be hesitant to register with a party for fear of being plagued by the endless mailings, robo-calls, and other fund-raising drives that characterized the last presidential election.

"There are a lot of people who were really disgusted with the things that went on," she said. "It wouldn't surprise me if people want to do what they can to avoid that."

Contact Allison Steele at 610-313-8113 or asteele@phillynews.com.