HARRISBURG, Pa. — Pennsylvania’s tax collections during the all-important month of April were badly lagging projections Tuesday, and House and Senate Appropriations Committee officials said the only question was how much deeper the state government’s shortfall will plunge.

The poor performance is a sobering development for Gov. Tom Corbett and lawmakers as they try to craft a budget during an election year. Based on estimates by House and Senate Appropriations Committee officials, the shortfall is expected to be big enough to knock Corbett’s $29.4 billion budget proposal out of balance by $1 billion or more.