The year 2006 was disastrous for Republican House candidates, and nowhere was the carnage worse than in Pennsylvania. The Republicans lost four House seats along with Rick Santorum's Senate seat, the biggest shift in the nation.

This year the Democrats, who hold an 11-8 edge in the state delegation, don't expect the same kind of gains, but they still hope to pick off one or two more GOP veterans, including two established incumbents in Western Pennsylvania -- Rep. Tim Murphy, of Upper St. Clair and Rep. Phil English, of Erie.

Roughly half a dozen of the state's 19 House seats are expected to be in play this year -- most of them held by Democrats, thanks to the party's successes in swing districts, such as Rep. Jason Altmire's upset of his current challenger, former Rep. Melissa Hart, the last time around.

Confounding GOP hopes that the pendulum was bound to swing back were three House special elections this spring, in Illinois, Mississippi and Louisiana, in which traditionally safe Republican districts fell to the Democrats.

The serial defeats prompted public soul-searching in the GOP hierarchy. Rep. John Boehner, the minority leader, promised action to respond to "a change election."

One of the GOP caucus' first re-packaging decisions sparked derision, however. Critics gleefully noted that the new slogan -- "the change you deserve" -- was already the motto of an anti-depression medication.

John Brabender, a media strategist advising a number of GOP House candidates in Pennsylvania and across the nation, cautions against concluding too much from the separate, isolated contests this spring, but acknowledged that their collective results can't be dismissed.

"Those were unique cases," he said. "In some cases, the candidate was not the best candidate in the world, but those were districts where even a flawed candidate should have won -- I do think it's a wake-up call."

Fewer Republican House members feel secure this year as they contend with headwinds generated by an unpopular war and a president with historically low negative ratings. But GOP partisans, as well as some neutral observers, argue that the recent Republican history does not mean that the fall will follow the same pattern.

"President Bush was [figuratively] at the top of the ticket in 2006; John McCain will be at the top of the ticket in 2008," said Mr. Brabender.

Nathan Gonzales, political editor of the nonpartisan Rothenberg Political Report, observed that the results of the special elections "prove that we are still in the 2006 election environment."

"Republicans still have problems with voters in the middle as well as socially conservative Democrats they've enjoyed support from in the past," he said.

But the analyst said that it's still difficult to forecast the political environment for the fall. Discussing the GOP's three special election setbacks, he said, "In the context of the Pennsylvania races, it doesn't change much today."

David Wasserman, the House editor for the Cook Political Report, another nonpartisan newsletter, cited one potentially crucial distinction between those contests and the broader competition for House seats in the fall. In each of the special elections, he noted, Democratic turnout was high, just as it had been in the Democratic primaries this year. Republican turnout lagged. Historical patterns suggest that that differential will be much smaller with the presidential election at stake.

"Turnout in November is universally high," Mr. Wasserman said. "In these races it was unilaterally high for the Democrats."

For the Republicans, the top Pennsylvania targets are in the districts they forfeited two years ago. Chief among them is Rep. Chris Carney, the Democrat who ousted former Rep. Don Sherwood in the 10th District, which sprawls over the state's northeast corner. Following the 2000 Census, the seat was redrawn to make it a virtual fortress for the GOP incumbent.

No Democrat could be found to run against Mr. Sherwood in 2002 and 2004. But after an ugly lawsuit filed by an ex-mistress raised a question or two about Mr. Sherwood's family values, Mr. Carney was able to find a place in the Democratic tide in 2006.

The district's GOP potential drew a big field of Republican challengers this year. Businessman Christopher Lawrence Hackett prevailed in an expensive and hotly contested primary and has the resources to wage what promises to be a competitive campaign against the freshman Democrat. This is the Pennsylvania race most often cited as a race to watch by neutral observers, including the Cook and Rothenberg publications.

The 4th District, north of Pittsburgh, offers a compelling story line in the state's only rematch. Ms. Hart, who was a rising star in the GOP majority before the 2006 results ousted both, is banking on her district ties and name recognition as she attempts to reclaim the seat. But it is Mr. Altmire who has the advantages of incumbency this time around, including the prospect of raising significantly more money than his challenger.

Federal Election Commission data showed that on the eve of the primary in which neither had an opponent (former county Councilman Ron Francis had dropped from the GOP race and endorsed Ms. Hart) the incumbent had raised $1.6 million and had $1.3 million in cash on hand. Ms. Hart had raised $529,081, and had a cash balance of $393,396.

That financial imbalance points to another concern for Republican candidates across the country. In contrast to past election cycles, the DCCC has far out-raised the NRCC this year, meaning that fewer GOP candidates can expect national cash to supplement their own war chests.

The other new Democrats in the state's delegation represent districts in the Philadelphia suburbs that have been trending toward their party after generations of Republican dominance. Rep. Joe Sestak, a retired admiral, is regarded as the safer of the two veterans. Rep. Pat Murphy, the only Iraq veteran now in Congress, may have a tougher battle. Part of Mr. Murphy's appeal rests on his military background. His challenger, Pat Manion, is a retired Marine colonel whose son was killed last year while serving a second tour of duty in Iraq.

This district, the 8th, is dominated by Bucks County and includes a small slice of Philadelphia. Larry Chiseler, a Philadelphia political analyst, noted that Mr. Murphy actually lost the Bucks County portion of the district two years ago, but was carried to a close victory by his dominance in Philadelphia. Since then, however, Bucks County's registration advantage has switched to the Democrats.

Perhaps the only non-freshman Democrat with the potential for a competitive race is Rep. Paul Kanjorski. Louis Barletta, who, as mayor of Hazleton, Pa., won national headlines for his opposition to illegal immigration, opposes him. Mr. Kanjorski's critics have circulated videotape in which he acknowledges that in pursuit of the House majority in 2006, Democrats exaggerated their ability to bring an end to the war in Iraq.

Two Western Pennsylvania Republicans, Mr. English and Mr. Murphy, are near the top of the Democratic priority lists. Both survived previous challenges with relative ease, but Democratic officials say that they face stronger candidates with more fund-raising ability this time around.

Businessman Steve O'Donnell emerged from a multi-candidate field that included the daughter of former Auditor General Barbara Hafer to win the right to take on Mr. Murphy. This district, the 18th, has a nominal Democratic registration edge, but it gave a majority to President Bush twice. The president, in fact, did better there in 2004 against Sen. John F. Kerry than he had against former Vice President Al Gore in 2000. Mr. O'Donnell can be expected to remind voters of charges that Mr. Murphy's public staff improperly mixed governmental and political work. The charges, based in part on the comments of a staffer he has since fired, surfaced shortly before the 2006 election.

While they put Mr. Murphy on the defensive they had did little apparent harm to his re-election bid, which he won in a landslide.

"This could end up being a race to watch, but right now we don't see it as a first, or even second tier race for the Democrats," said the Rothenberg report's Mr. Gonzales.

Mr. English, first elected in 1994, hasn't had a tough election in more than a decade. This year, however, Democrats claim that his district, which extends from Erie to Pittsburgh's northern suburbs, is ready for a change. His challenger is Kathy Dahlkemper, a first-time candidate. Ms. Dahlkemper, the director of the Lake Erie Arboretum, won a four-way Democratic primary.

Stephen Porter, the unsuccessful Democratic nominee for the seat in the past two elections, is running this year as an independent.

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