Wise strategists need look no further than U.S. House races in Pennsylvania to gauge the country's political temperature.
In the past decade, Pennsylvania has been a Democrat-leaning presidential battleground. It went for Gore (51-46), Kerry (51-48) and Obama (55-44).
"Putting these numbers in perspective, the state tends to vote about 4 percentage points more for the Democratic nominee than the nation as a whole does," says Lara Brown, Villanova University professor.
Democrats have been increasingly confident that trend will continue, given 2006 midterm and 2008 general election wins. But change can come quickly.
Brown says a few Keystone State congressional seats Democrats hoped to win (districts 6 and 15) or were confident of keeping (7, 10 and 11) are beginning to trend against them.
RealClearPolitics' average for the generic ballot favors Republicans by 3 points.
If that's accurate, Brown explains, "Then in Pennsylvania what you can infer is that among likely voters, Democrats are only running ahead of Republicans by about 1 percentage point."
In other words, the state is extremely competitive and may -- depending on primary races -- again seem like a political "ground zero" come October.
Nine of 19 House districts are stone-cold safe for incumbents. A breakdown of the other 10 House races:
• Rep. Kathy Dahlkemper, D-3, defeated seven-term incumbent Phil English in 2008 because of an anti-GOP year and a great Democratic Congressional Campaign Committee effort. She needs a better campaign this time.
• Rep. Jason Altmire, D-4, has raised more than $1.2 million, yet his votes in line with his moderate constituency have progressive Democrats seeking a primary challenger. That leaves former U.S. Attorney Mary Beth Buchanan, a Republican, to knock on doors and make friends in a district that has trended Republican in two consecutive cycles.
• Rep. Jim Gerlach, R-6, deciding to seek re-election (instead of running for governor) probably keeps this southeastern seat for the GOP -- unless he's upset in the primary. Democrats Doug Pike, a former Philadelphia Inquirer editorial writer, and Manan Trivedi, a primary-care doctor and Iraq War veteran, are in a nasty primary battle to run against him.
• Rep. Joe Sestak, D-7, is running for U.S. Senate, so the race for the southeastern House seat he's vacating is open -- and competitive, between Philly's former U.S. attorney, Republican Pat Meehan, and the Democrats' primary winner. Long a GOP district (with a few exceptions), it leans strongly Republican this year.
• Rep. Patrick Murphy, D-8, faces a surprisingly competitive race against the guy he unseated in 2006, Mike Fitzpatrick, who wisely waited out 2008. Lack of Democrat enthusiasm puts Murphy at risk, despite impressive fundraising.
• Rep. Chris Carney, D-10, should -- on the surface -- be safe because the GOP hasn't recruited well. Yet this northeastern race is competitive.
• Rep. Paul Kanjorski, D-11, is in trouble -- but only if Hazleton Mayor Lou Barletta, a Republican, has a real message beyond immigration. This race is all about how Kanjorski's pork hasn't created any jobs.
• Rep. Jack Murtha, D-12, isn't going anywhere unless he decides to retire from his southwestern seat, which is highly unlikely.
• Rep. Charlie Dent, R-15, always has a competitive race. He faces a real challenge from Bethlehem's mayor in the state's truest battleground, the Lehigh Valley.
• Rep. Tim Holden, D-17, faces his toughest challenge since the redistricting fight of '02, with Republican state Sen. David Argall in the race.
In 2006, a national tide swept ruby-red suburban areas away from Republicans and to Democrats. Pennsylvania's competitive seats have been emblematic of national political shifts.
What House races in Pennsylvania show is that freshman and sophomore Democrats nationwide are vulnerable. Incumbents of each party should be wary of being tossed out by frustrated voters.