LOS ANGELES — Signaling that California is slipping deeper into financial crisis, the state’s controller said Wednesday that his office would soon be forced to issue i.o.u.’s to scores of the state’s creditors, as lawmakers failed at their first attempt as a body to close the state’s multibillion-dollar shortfall. If the i.o.u.’s are issued as threatened, it would be the first time since 1992 — when Gov. Pete Wilson paid roughly 100,000 state employees with them — that the warrants were used to hold over those to whom the state owed money. Before that budget crisis, California last issued the warrants during the Depression. “Next Wednesday we start a fiscal year with a massively unbalanced spending plan and a cash shortfall not seen since the Great Depression,” the controller, John Chiang, said in a written statement. He added, “Unfortunately, the state’s inability to balance its checkbook will now mean short-changing taxpayers, local governments and small businesses.” The issuing of the i.o.u.’s would reflect the state’s lack of cash flow and its Legislature’s inability to agree on a way to close the roughly $24 billion budget gap, as tax revenues have continued to fall.