GOP lawmakers approved some $2 billion in tax cuts over the past four years but since those cuts were largely phased in over time, they are now contributing to the projected future shortfalls by 2017, says Dale Knapp of the Wisconsin Taxpayers Alliance.

“We really can’t say for sure what is driving this deficit but the economy might be growing more slowly than we thought, the (M&A) tax credit could be bigger than we thought and the cost of the income tax cuts could be bigger than we thought,” he says.

The M&A tax credit in particular drew fire at the time it was approved in Walker's first two-year budget in 2011. Phased in over four years it was projected to reduce taxes on those business owners by $360 million initially and $130 million each year going forward.