With so much at stake, both parties have been feverishly fund-raising, spending, and strategizing to get voters to pull the lever for them Nov. 2.
And each side is cautiously, but openly, proclaiming it will win.
"We're excited about the candidates we're running, and we feel we've run smart, aggressive campaigns that will help us maintain the majority," said Rep. Mike Gerber (D., Montgomery), who chairs the House Democrats' campaign committee.
Not if Rep. Dave Reed (R., Indiana) has anything to say about it.
Reed, who heads the House GOP's campaign committee, said last week that Democrats weren't just sailing into fierce national headwinds - they also didn't have an established Democratic name, such as President Obama or Gov. Rendell, on the ticket.
He and other GOP strategists like to point out that historically, Republican voters turn out in greater numbers in midterm elections. Add to that a growing dissatisfaction with Obama, and they could dominate at the polls.
"People are going to get out and vote this year," said Reed, "and they're angry."
But angry at whom? Perhaps incumbents of both parties. From the legislative pay raise of 2005 to the so-called Bonusgate scandal and the state's budget woes, polls indicated that the low opinion of the General Assembly predated the recession and Obama.
In addition to the House, half the 50 seats in the Senate are up for grabs, not including a special election to fill the seat of a retired Western Pennsylvania senator.
And though there are contested Senate races - 15 incumbents face challengers - there is little chance that the balance of power will flip. Republicans hold a comfortable 30-19 majority in the upper chamber.
In the House, 17 seats are open. Among incumbents, 109 are in contested races, and 77 have no opponent.
Democrats and Republicans involved in those races say the battle for the House comes down to geography: The GOP hopes to pick up seats in the Philadelphia suburbs held by freshman or sophomore Democrats, while Democrats need to minimize their losses in those suburbs and in the western end of the state - which has been trending conservative - while picking off a few seats occupied by Republicans.
One such targeted seat is that of former House Speaker John Perzel (R., Phila.), who is locked in a fierce fight with Democrat Kevin Boyle to keep his job.
Democrats have put a big bull's-eye on Perzel's back. They hope to capitalize not only on his fall from House leadership in recent years, but also on his legal problems: Perzel awaits trial on charges in the so-called Bonusgate scandal. He is accused of misusing public money for campaign purposes.
He has repeatedly said he did nothing wrong and is fighting the charges.
In an interview last week, Perzel told of spending the last three months pounding the pavement in the hope of knocking on the doors of all 19,000 homes in his Northeast Philadelphia district.
The last time he did that kind of ground-level campaigning was 1978, he said - the year he was first elected.
"Right now, I feel comfortable," Perzel said of his chances of reelection. "What I'm hearing when I go door to door is that people are going to get out and vote for me."
Another onetime House speaker seeking reelection while fighting criminal charges is Rep. Bill DeWeese (D., Greene). He, too, is optimistic that he will be back in the Capitol next year - thanks to what he calls "the cumulative enthusiasms and stewardships of my past service, amalgamated with what are perceived by the body politic to be very dubious, politically motivated charges."
Battleground House races in the Philadelphia suburbs include Rep. Barbara McIlvaine Smith (D., Chester) against Dan Truitt, Rep. Paul Drucker (D., Montgomery) against Warren Kampf, Rep. Steve Santarsiero (D., Bucks) against Rob Ciervo, Rep. Matt Bradford (D., Montgomery) against Jay Moyer, and Rep. Rick Taylor (D., Montgomery) against Todd Stephens.
G. Terry Madonna, veteran pollster at Franklin and Marshall College, said that given the political stakes, voters could expect to hear a lot in the next few weeks about these and other legislative races.
For starters, there is redistricting. State legislative and congressional districts are redrawn every 10 years based on the census. The process will start in earnest with the new legislature next year.
If the GOP controls both chambers, the party could redraw the maps to benefit its candidates.
Beyond that, said Madonna, if Republicans gain control of the House and the governor's office in addition to the Senate, "we would have a repeat of the 1995-to-2003 era, when Gov. Ridge and the Republicans owned Harrisburg and did very little negotiating with Democrats."
He added: "Who wins the House and the governor's office this year is a huge consideration for what will get done in the state in the next few years. It's about priorities: Will they be Democratic priorities, or Republican?"
Contact staff writer Angela Couloumbis at 717-787-5934 or firstname.lastname@example.org.