To win Pennsylvania, Sen. John McCain aims to reverse one historic trend while reinforcing another.

The soon-to-be GOP nominee needs to emphasize the crossover appeal that comes with his maverick image to stem Republican erosion in the southeastern corner of the state.

At the same time he needs to burnish his conservative credentials to capitalize on increased GOP strength in western and rural areas.

"This is not a complicated chess game," said Terry Ma-donna, director of Franklin and Marshall College's polling operations. "It's pretty clear where you have to move the pieces.''

Democratic candidates won the state's electoral votes in each of the last four presidential elections, although President Bush twice managed to make it close. Former Vice President Al Gore won the state's popular vote, 51 percent to 46 percent, in 2000. Four years later, Sen. John F. Kerry won, 51 percent to 48 percent.

This year, Republican partisans argue, Mr. McCain has a chance to better Mr. Bush's record and even win the state because of what they see as his greater appeal to independents. He'll need all of that appeal in a state that is, by registration, more Democratic than in either of the last two elections.

"The registration [change] has been dramatic,'' said Mark Holman, chief of staff to former Republican Gov. Tom Ridge. "I suspect our base vote is below 40 [percent], and it used to be in the mid-40s. That's a structural challenge for Republicans. Republicans are going to have to win more Democratic votes in Pennsylvania, but that's the beauty of the McCain candidacy."

"John McCain is a different kind of Republican," said Jon Seaton, the McCain campaign's regional director for Ohio and Pennsylvania. "He draws votes from Republicans, Democrats and Independents.''

Shifting tides

Perhaps the most significant state voting shift over the last 15 years is the change in the performance of the four suburban counties surrounding Philadelphia. Once a GOP stronghold, these areas, which have enjoyed relatively high economic and population growth, have proved increasingly hospitable toward Democratic candidates.

In the Republicans' favor is a countervailing trend in areas of slower population growth. In balancing those dynamics, Republican strategists said, Mr. McCain will have to run a very different race than the man he hopes to succeed. Mr. Bush's reelection campaign in Pennsylvania concentrated on maximizing turnout among his party's conservative base.

He lost the Philadelphia region, including the city and its suburbs, by the landslide margin of 59 percent to 41 percent. But, buoyed by a huge turnout of Republicans in the balance of the state, the president still came within about 150,000 votes of overtaking Mr. Kerry.

Mr. McCain has a different challenge, and a different roadmap to success.

"The one thing we see is that more of the state will be in play than in past statewide elections," said Ted Christian, Mr. McCain's Pennsylvania director. "He has a great chance in the Philadelphia suburbs. He can also play well in places like Beaver, Lawrence, even Cambria County."

Mr. Christian is familiar with the challenges of suburbs becoming friendlier to Democrats from his past role as executive director of the New Jersey state Republican party. His colleague Mr. Seaton is a veteran of the near-demise and Phoenix-like revival of the McCain fortunes. He was the campaign's national field director until a shake-up and down-sizing last summer. He soldiered on as Iowa field director at a time when the campaign had turned most of its energies to New Hampshire.

The Clinton lesson

Mr. Seaton sees another template for McCain votes in the results of the state's Democratic primary, where Sen. Hillary Rodham Clinton, though badly outspent, defeated Mr. Obama by just over 9 percentage points.

"You look a the places where Obama struggled in the primary. ... I would expect to see Sen. McCain do well there too,'' Mr. Seaton said.

It's no surprise that the McCain campaign will use some of the same issues that brought victory to Mrs. Clinton. At his last Pittsburgh appearance, earlier this month in the Strip District, Mr. McCain said he would remind Pennsylvania voters that he did not agree with Mr. Obama's well-publicized observation that some small-town residents in Pennsylvania "cling to" such cultural traditions because they are "bitter'' over their economic circumstances. Mrs. Clinton used the controversy surrounding those remarks to her advantage.

The only congressional district outside the Philadelphia area that Mr. Obama won in the primary was the 14th, which includes Pittsburgh and parts of the Mon Valley. Mr. Obama piled up a big margin in Philadelphia, but Mrs. Clinton bested him, albeit narrowly, in the city's suburbs.

She managed a narrow victory in the 7th Congressional District, which includes Delaware County, and won easily in the 13th and 8th districts, which include Montgomery and Bucks counties.

While polls suggest that most of the Clinton votes will go to Mr. Obama, the McCain advisers are heartened by the fact that Mr. Obama didn't win them in April.

John Brabender, the prominent Republican media strategist, said Mr. McCain has "to play up his independent image and independent voting record. He's got to make sure that people understand he is in no way an extension of the George Bush presidency, which, I think, Obama wants to make this a referendum on.''

Underscoring that danger to the Republican, Mr. Madonna, the Franklin and Marshall pollster, said that his recent surveys had shown that "this thing with Bush is lethal in the Philly suburbs.''

"Bush is more unpopular in those suburbs than in the rest of the state and the Iraq war is more unpopular there than in the rest of the state,'' he said.

Mr. McCain has emphasized his distance from the president on a variety of issues, including the earlier, pre-Surge conduct of the war. But he has been adamant in his overall support of the war.

""If you look at Philadelphia and the four surrounding counties, Bush lost very big. ... We have a candidate in John McCain who can improve on that,'' said Mr. Seaton.

It would be difficult, however, for Mr. McCain to improve on the Bush margins in some of the rural, central and western counties that nearly allowed the president to overtake Mr. Kerry four years ago.

Mr. Holman, an architect of Tom Ridge's two statewide victories, sees three corners of the state -- the northeast, northwest and southwest -- as fertile territory for Mr. McCain. He cited that all three areas' relatively's older electorate and significant veterans' population as likely sources of strength for the Republican.

"The wild card is turnout in Central Pennsylvania,'' he said. "President Bush ran extraordinarily well out of Lancaster County and Central Pennsylvania. I don't know if there's the same excitement for McCain in the evangelical community. It's a surmountable challenge but it's a challenge.''

What about Ridge?

One thing that could help the Arizonan in Pennsylvania hurdles would be the choice of Mr. Ridge as his running-mate. Neither Mr. Holman nor the McCain strategists would comment on that possibility, but it seems clear that a Ridge pick would aid the ticket in areas such as the socially liberal Philadelphia suburbs. But the selection of the pro-choice Ridge would be certain to provoke an outcry in the party's socially conservative base.

Mr. Brabender, who worked on Mr. Ridge's first congressional campaign, contends that the Ridge plusses outweigh his liabilities. And while he emphasized that he was not predicting that choice, he said it was not beyond the realm of political possibility.

"Obviously, if Tom Ridge were picked, it would be a huge boost,'' he said.

And, looking at the national picture, he suggested that the lesson of Mr. McCain's primary journey from seeming disaster to unlikely triumph showed the virtue of the unorthodox.

"When they tried to go the traditional route, things didn't work out too well. When he tried to be a little bit of a renegade, breaking the rules, things worked out better.''

Mr. McCain has buttressed his chances in Pennsylvania with early television advertising. The campaign has so far opened 10 offices in the state and Mr. Seaton said more sites were planned. Mr. McCain's fourth television commercial began airing in Pennsylvania and ten other states this weekend. He has already made multiple post-primary appearances in the state and will return in mid-week for another visit to the vote-rich Philadelphia region.

"You're going to see him again and again and again,'' Mr. Seaton predicted.

Next Sunday: Barack Obama's roadmap to a victory in Pennsylvania.