WILLIAMSPORT, Pa. — David Butler voted for Richard Nixon in 1972, then kept voting for GOP candidates through Watergate, Reaganomics and the Bill Clinton years.
This year, though, the 59-year-old teacher switched his registration to Democrat, and he said he plans to vote Tuesday for Illinois Sen. Barack Obama.
Since Jan. 1, more than 178,000 people in Pennsylvania have changed their party affiliations, and 92 percent of them have gone from Republican or independent to Democrat.
Some 4.2 million Democrats are eligible to vote in Tuesday's presidential primary, and the Pennsylvania Department of State predicted Monday that turnout could be as high as 50 percent.
If a big chunk of the party-switchers side with Obama, they could give him a decided edge.
That edge is hard to quantify, however. "While the switch is being driven by a number of factors, it's clear Obama's creating excitement," said Brad Coker, managing partner of Mason-Dixon Polling & Research.
New York Sen. Hillary Clinton led Obama by 48-43 percent, with 8 percent undecided and an error margin of plus or minus 4 percentage points in the latest Mason-Dixon poll conducted late last week for McClatchy, MSNBC and the Pittsburgh Post-Gazette. But anecdotal evidence is strong that the switchers are almost always Obama backers.
They've warmed to Obama for two key reasons: They find him inspiring, and they want sweeping change.
Frank Pellicone, a commercial real estate manager from Yardley, in the Philadelphia area, registered as a Democrat after he found that Obama reminded him of John F. Kennedy.
Pellicone, 59, was already souring on the Republican Party as he became disillusioned with the war in Iraq. Then he found that he was "glued to the TV when Obama speaks," and he made the change.
Some switchers decided to vote for Obama after last Wednesday's Philadelphia debate. They liked how Obama gently answered questions about his relationship with his former pastor and a '60s-era radical.
"I like that about him. I don't want all this fighting and backbiting," said Troy Knapp, who's self-employed in Williamsport, in north-central Pennsylvania.
"Obama's tone is appropriate," added Kelly Socling, a Williamsport small-business worker who changed from the Green Party.
A lot of party-switchers are fed up with the Republicans, the Iraq war, rising health care prices and soaring costs of energy, and they want someone who can shake up Washington.
Mark Clayton was struck by the interest Obama stoked in Dan, his 17-year-old son. So Clayton, a suburban Philadelphia fuel oil dealer and a Republican, decided to take a closer look.
Clayton knows first hand about economic peril, as rising oil prices hurt not only his pricing, but also his customers' ability to pay.
So his choice became clear: "I'm a business owner," Clayton said, "and the nation needs change."
In Scranton in northeastern Pennsylvania, Craig Churchill Jr., 20, said he wanted the opposite of the Bush administration. In Doylestown, near Philadelphia, Maureen Gore, who once worked for President Ford's campaign, found that while Obama may not have any better answers than anyone else, "I just feel like he's a good, decent man."
Such switchers aside, Clinton retains a strong core of lifelong, hardcore Democrats. That core, said Coker, remains the key to her strength.
"Clinton's more middle of the road," said Elaine Boal, a retiree from Clearfield, and people in the small northern and western Pennsylvania towns appreciate that.
Joseph Syktich, a Houtzdale retiree, has fond memories of Bill Clinton and wants him to wield some influence again.
"He had the country in good shape, and Hillary makes a lot of sense," Syktich said.
Neither Boal nor Syktich were party switchers; they're loyal Democrats.
But there's unquestionably a huge army of switchers out there, even in places such as Clearfield, and Obama's fate could well be tied to how many people are thinking like Butler, the Mansfield teacher.
He remembers leaving college when he was young so he could go home and vote for Nixon. He stuck with Ronald Reagan in the 1980s because "I liked his economic policy, and he cared about people."
He was less enthusiastic about George W. Bush, but remained a registered Republican — until now.
Obama, Butler said, "understands what it's like to be at the lower end of the economic scale. And he's concerned about the war in Iraq.
Most of all, he said, "I just don't like the Bush administration."