The slim, 5-vote control of the state House by Democrats is one of many in the balance nationwide, and things are looking rather grim for Barack Obama's party, says Louis Jacobson in Governing mag:

This fall's legislative elections -- the last before the start of a new once-every-decade redistricting process -- are unique for two reasons. According to this author's estimates, more chambers are in play this year than in any cycle since at least 2002. Even more strikingly, the Democrats have vastly more at risk than the Republicans do.

"This is going to be an extremely challenging year for Democrats for a variety of reasons," says Tim Storey, who analyzes elections for the National Conference of State Legislatures. "History is not on their side. Since 1900, the party in the White House loses seats in the legislature in every midterm except for 1934 and 2002. That's a 2-25 losing streak for the party in the White House -- a tough trend to break. Add to that the fact that Democrats are riding high right now at over 55 percent of all seats, and it shapes up to be possibly the worst election for Democrats since 1994."

Jacobson says Democrats have 18 chambers that could switch control nationwide, while Republicans have just four. The state Senate is solidly GOP, and he currently rates control of the state House as a tossup:

The state Senate is solidly Republican, but the Democratic majority in the state House is as fragile as they get. Republican Tom Corbett leads Democrat Dan Onorato in all polls, conforming to an eight-years-and-out pattern for party control of the governorship that has prevailed since World War II. Add in the lingering effects of the "Bonusgate" scandal (which hit Democrats harder) and the impending exit of Democratic Gov. Ed Rendell from the stage (which removes a big Democratic asset in southeastern Pennsylvania) and all signs point to a severely stressed Democratic hold on the House. Rate the chamber a tossup for now, but that could easily switch to lean Republican by our next rating.