By Greg Giroux, CQ Staff

Pennsylvania should be a hotbed of competition in U.S. House races this year, as the roster of candidates who met a Thursday afternoon qualifying deadline makes clear.

Republicans would like to win back some of the four districts in which Democratic challengers unseated Republican incumbents in the 2006 election. Those gains enabled Democrats to turn a 12-7 Republican advantage in the state’s U.S. House delegation into an 11-8 Democratic edge in the current 110th Congress.

Democratic strategists think they can make even more inroads in the current Pennsylvania congressional map, even though it was drawn by Republican legislators at the beginning of this decade to lock in a decade-long partisan advantage for the GOP.

All but one of Pennsylvania’s 19 members of the U.S. House of Representatives is seeking re-election and none is challenged in the April 22 primary election, according to an unofficial list of candidate filings provided by Pennsylvania’s state elections office. The real challenge to the incumbents will come after the primaries.

The lone retiree in the Pennsylvania delegation is six-term Republican Rep. John E. Peterson , who is not seeking re-election in the 5th District, a vast north-central district that takes in State College and small towns. This is staunchly Republican turf — President Bush took 61 percent of the district vote in 2004 — and it’s highly likely that the winner of the Republican primary will succeed Peterson in Congress. CQ Politics presently rates this race as Safe Republican.

The nine-Republican candidate field includes Chris Exarchos, a former Centre County commissioner; John Krupa, an insurance agent; Lou Radkowski, the Elk County coroner; Keith Richardson, a lawyer and pastor; Matt Shaner, a businessman and former aide to Republican Sen. Rick Santorum (1995-2007); Jeff Stroehmann, a businessman; John Stroup, the mayor of Clarion; Glenn W. Thompson, the chairman of the Republican Party in Centre County, which includes State College and Penn State University; and Derek Walker, a financial planner.

Despite the district’s underlying conservatism, three credible Democratic candidates are running: Bill Cahir, a journalist who is also a veteran of the current Iraq War; Mark McCracken, an elected commissioner in Clearfield County; and Richard P. Vilello Jr., the mayor of Lock Haven.

But at least six districts promise much greater two-party competition.

In the 4th District near Pittsburgh, former Rep. Melissa Hart is challenging Democratic Rep. Jason Altmire in a rematch of a 2006 campaign that Altmire won by 4 percentage points.

During the 2006 campaign, Hart appeared to take Altmire too lightly and didn’t draw sharp contrasts with him until it was too late. She’s taking a different tack as the challenger, recently releasing a Web video that attacks Altmire on tax and spending issues and linking him to House Speaker Nancy Pelosi of California and Massachusetts Sen. Edward M. Kennedy , two of the most prominent liberals in Congress.

In the northeastern 10th District, freshman Democratic Rep. Christopher Carney will face the winner of a three-candidate Republican primary that includes businessmen Dan Meuser and Chris Hackett as well as Davis Haire, an optometrist. This district is the most heavily Republican-leaning district in Pennsylvania that is represented by a Democrat.

At the moment, the 4th and the 10th appear more competitive than the other two districts — both in the Philadelphia region — that Democrats wrested from Republican control in 2006.

In the 8th District, which is dominated by Bucks County north of Philadelphia and includes a small part of the city, Rep. Patrick J. Murphy probably will square off in November against Tom Manion, a retired Marine Corps colonel whose son was killed in Iraq last April. Murphy is the only Iraq War veteran currently serving in Congress.

Manion is opposed in the Republican primary by Joseph Montone, who lost a Republican primary in the 8th District in 2004 and also was unsuccessful in 2006 in a state House race.

In the 7th District, which takes in most of Delaware County west and southwest of Philadelphia, freshman Democratic Rep. Joe Sestak is an exceptionally well-funded incumbent whose district has been steadily trending Democratic. He will face Republican W. Craig Williams, a former federal prosecutor; neither faces opposition in the primary.

A competitive race may yet surface in the northeastern 11th District, where Hazelton mayor Lou Barletta recently announced that he will challenge 12-term Democratic Rep. Paul E. Kanjorski . Barletta, who has attracted attention for his efforts to curb illegal immigration in his community, also opposed Kanjorski in 2002 and lost by 13 percentage points.

DEMOCRATIC EFFORTS TO WIN REPUBLICAN-HELD SEATS

Though the Democrats will be playing a lot of defense in Pennsylvania this year, they have some opportunities to augment the gains they made in the 2006 election.

In the northwestern 3rd District, four Democrats filed to challenge Republican Rep. Phil English : Kathy Dahlkemper, the director of the Lake Erie Arboretum; Kyle Foust, a member of the Erie County Council; Tom Myers, a lawyer; and Moise “Mike” Waltner, a program coordinator at the Episcopal Cathedral of St. Paul in Erie.

Dahlkemper got into the race after the other Democratic candidates, but she reported raising the most money and had the most cash-on-hand of the Democratic candidates as of the end of last year.

In Pennsylvania’s 6th District, Republican Rep. Jim Gerlach has won each of his three elections by the same 51 percent to 49 percent margin — outcomes that reflect the general competitiveness of a district that includes a mix of urban, suburban and rural communities west and northwest of Philadelphia. Gerlach is one of just eight House Republicans who represents a district that President Bush did not win in his 2004 re-election victory over Democratic Sen. John Kerry of Massachusetts.

The three Democratic candidates challenging Gerlach are Mike Leibowitz, a real estate executive who lost a 2006 primary to Democratic lawyer Lois Murphy, who lost to Gerlach in 2004 and 2006; Bob Roggio, a businessman and veteran Democratic campaign activist; and Bob Rovner, a lawyer and former state senator.

One of the other seven “Kerry-Republican” districts is Pennsylvania’s 15th, which takes in Allentown, Bethlehem and other territory in the Lehigh Valley and is represented by two-term Republican Rep. Charlie Dent . Elected convincingly in 2004, Dent won more modestly in the anti-Republican 2006 election year, when he was opposed by a Democrat who qualified for the November ballot after the original filing period expired.

The Democrats’ 2008 candidate will be Siobhan “Sam” Bennett, a local party activist who twice ran unsuccessfully to be mayor of Allentown.

Like English, Republican Rep. Tim Murphy , who represents the 18th District near Pittsburgh, hasn’t received vigorous Democratic opposition in recent election years. Four Democrats hope to give him a tougher race: Wayne Dudding, a colonel in the U.S. Army Reserves and an Iraq war veteran; Beth Hafer, an executive in the consulting firm founded by her mother, former Pennsylvania Treasurer Barbara Hafer; Steve O’Donnell, a businessman; and Brien Wall, a life insurance company employee.