In 2006, Pennsylvania bled Republican red.

No state in the country produced more GOP congressional losses, as four Keystone State House districts joined Rick Santorum's Senate seat in shifting to Democratic control.

Pennsylvania Democrats have high hopes of picking off another Republican incumbent Tuesday in an election cycle that is expected to add to the Democrats's 36-seat House majority.

Rep. Phil English, R-Erie, in the fight of his political life against a challenge from the Democrats' Kathy Dahlkemper, fits that national pattern.

But, surprisingly, Pennsylvania may also be the only state in the nation in which two veteran Democratic congressmen are in jeopardy of losing their seats.

Last month, former President Bill Clinton joined Sen. Hillary Rodham Clinton in Scranton in their first joint appearance for the Obama campaign. His first words weren't about Sen. Barack Obama, or the city's newly celebrated native son, Sen. Joseph R. Biden Jr.

Instead he issued a warning for the Democratic crowd.

"Folks, Paul Kanjorski's got a tough race," he said. "He's got a tough race because some people in his district believe that illegal immigration is a bigger cause of their economic problems than President Bush's economic policies. I've got news for them and I've got news for you -- you need to help him get re-elected."

Last week, the former president was in Washington, Pa., with a similar plea for another Democratic warhorse.

"The only way [Rep. John Murtha] can lose this, is if people stop thinking," he said. The race, however, is effectively a referendum on the appropriations powerhouse who has represented the district since 1974, Mr. Murtha faces a newly invigorated challenge from Republican William Russell, an army veteran.

(Mr. Clinton is stumping for both candidates again tomorrow.)

Mr. Murtha has provided the strongest arguments for and against his retention. His re-election, like the 16 before it, seemed a given until his remarks at a Post-Gazette editorial board meeting last month in which he suggested, while analyzing the presidential contests, that many of his constituents were "racist."

Northeastern rematch

Mr. Kanjorski, who's serving his 12th term, is in a rematch with Lou Barletta, the mayor of Hazleton who attracted national headlines as a champion of anti-immigration legislation in his northeastern Pennsylvania city.

Mr. Kanjorski defeated Mr. Barletta handily in 2002, but this year's looks like a much closer race. A Franklin & Marshall College Poll earlier this month showed the veteran trailing Mr. Barletta by five points, 40 percent to 35 percent, in a district that should be safe for any Democrat. Those figures, however, still represented a narrowing of the margin for the seat since an earlier F&M survey in September.

While noting that the outcome remained uncertain, Terry Madonna, director of the F&M survey, wrote in an analysis that "[Rep.] Kanjorski's vital signs do not augur well for him. The poll reveals that less than two in five (35%) registered adults in the district believe he deserves re-election -- a figure unchanged since September.

"Equally dire, Mr. Kanjorski's support among registered Democrats remains weak; only half of Democrats are planning to vote for him. By contrast his opponent is supported by about two in three Republicans and three in five independent voters."

The political scientist added, however, that the incumbent's prospects could be enhanced by a surge in support for the top of his ticket. The poll found improving numbers for Mr. Obama in a corner of the state that has been the focus of intense campaigning by both national tickets. In the view of most independent analysts, however, this district remains the GOP's best shot for a pickup in the state.

English in a fight

Ms. Dahlkemper, a businesswoman who is the director of the Lake Erie Arboretum, represents the Democrats' best opportunity to knock off a Republican incumbent in the state. The independent expenditure arms of both national campaign committees have spent money in the district, which President Bush carried twice. Mr. English won the seat after Tom Ridge moved into the governor's mansion in 1994.

He came to prominence in state politics along with Mr. Santorum and former Rep. Melissa Hart, both of whom he worked for at one time or another, and both of whom were victims of the Republican carnage of 2006. In Congress, however, he followed a less outspokenly ideological path than his former colleagues.

Ms. Dahlkemper has emerged as the toughest challenger of his career, however, and has portrayed him as a Washington insider while characterizing the district's generally sluggish economic growth as a measure of his effectiveness.

One independent poll, by SurveyUSA, found her leading, 49 percent to 45 percent last month. More recently, the English campaign pointed to a poll by the Republican firm, Public Opinion Strategies, depicting him with a narrow lead. What is clear in the conflicting numbers is that Mr. English is in real danger in a race that national Congress watchers have rated a tossup.

Hart attempts comeback

In an adjoining district, one of Mr. English's former bosses, Ms. Hart, appears to face tough odds in her bid to recapture the 4th District seat from Rep. Jason Altmire. The Republican has had a tough time finding an opening against a candidate whose voting record has largely reflected the concerns of the largely Democratic but socially conservative district.

While most analysts see the freshman Democrat as a safe bet for re-election, his district was carried overwhelmingly by Sen. Hillary Rodham Clinton in the Democratic presidential primary. The GOP presidential campaign views it as an area ripe for inroads with the strain of local Democrats that has produced regular majorities for national and statewide Republicans over the last decade.

"The challenge and opportunity for Melissa Hart is to go after those McCain voters,'' said John Brabender, her media strategist. "If she picks up the McCain votes in that district, she'll win the race."

Ms. Hart, who was a rising star in the GOP majority before 2006, is banking on her established name as she attempts to reclaim the seat. But it is Mr. Altmire who has the advantages of incumbency and money this time around.

Carney surprising

Rep. Chris Carney, not Mr. Murtha or Mr. Kanjorski, was once seen as the Democrats most vulnerable. Mr. Carney's 10th District, on the state's northeastern corner, was drawn to be a fortress Republican seat and might have remained so had its former representative, Republican Don Sherwood, not become involved in an ugly, since settled lawsuit over an extramarital affair.

Mr. Sherwood's defense to his constituents -- in essence, "I slept with her but I didn't strangle her."-- didn't lend itself to campaign bumper stickers.

In a recent Franklin & Marshall survey, Mr. Carney, a Navy Reservist, had a clear lead over challenger Chris Hackett, the survivor of a bitter and divisive Republican primary. Given the district's Republican tilt, no Democrat would ever be able to take it for granted, but the incumbent appears to be the clear favorite.

The other two Democratic pickups in 2006 were in Philadelphia suburbs that have been trending Democratic after generations of Republican dominance. Rep. Joe Sestak, a retired admiral who represents a seat based in Delaware County, is regarded as the safer of the two military veterans. He faces Republican Wendell Williams.

Rep. Pat Murphy, a former Army officer and Iraq war veteran appeared earlier in the year to face a tougher battle in his Bucks County seat.

His challenger, Pat Manion, is a retired Marine colonel whose son was killed while serving a second tour of duty in Iraq. Mr. Murphy, who has raised far more money than his challenger, was an early state supporter of the Obama campaign, and, in large part due to its organizing efforts, the Bucks County base of the 8th District has switched from a Republican to a Democratic majority since his first election.

Elsewhere in the state, incumbent House members appear reasonably secure. Among them is the state's other Murphy, Rep. Tim Murphy, the Upper St. Clair Republican who represents a largely suburban district south of Pittsburgh. Businessman Steve O'Donnell has mounted a spirited campaign against him, but analysts of both parties said they expected Mr. Murphy to ride the advantages of incumbency to re-election.

One wild card that could trump that expectation would be an unexpectedly large victory, and accompanying coattail effect, from the Obama campaign in a state in which Democratic registration has soared in the last year. Such an unexpected wave could, in theory, be enough to carry Mr. O'Donnell to an upset.

Other Republicans who now appear safe, but who could be buffeted by an unanticipated but not inconceivable landslide, include Rep. Jim Gerlach, and Charles Dent, both of whom represent mixtures of suburban and rural communities between the Delaware and Lehigh valleys, at the fringes of the Philadelphia media market.