CHICAGO (AP) — A Chicago-based research group says cleaning up Illinois’ budget mess will require difficult decisions such as raising the income tax, slashing spending and imposing taxes on food, services and some retirement income. In an analysis released Thursday, the Civic Federation’s Institute for Illinois’ Fiscal Sustainability says the state budget stalemate has only exacerbated Illinois’ enormous financial problems. Civic Federation President Laurence Msall says “there are no more politically popular solutions left.” Illinois faces a roughly $5 billion budget deficit this year. Its unpaid bill backlog could reach almost $26 billion by 2020 if current revenue and spending policies continue. The analysis recommends raising the individual income tax rate from 3.75 to 5 percent and amending the Illinois Constitution to allow future pension benefits to be cut, among other changes.