According to Walter J. Oleszek, a political science professor and "senior specialist in American national government at the Congressional Research Service",[3] omnibus bills have become more popular since the 1980s because "party and committee leaders can package or bury controversial provisions in one massive bill to be voted up or down.
[4] A "cromnibus" (portmanteau of "CR" and "omnibus") is a bill setting new funding levels for certain sectors of the federal government, while renewing the previous fiscal year's ones for others.
These bills appropriate money to operate the federal government and make national policy in scores of areas.
These omnibus bills grant large powers to a small number of people who put these packages together - party and committee leaders and top executive officials.
Absent enactment of annual appropriation bills or a CR, federal agencies must shut down, furloughing their employees.
Moreover, "uncertainty about final appropriations leads many [federal] managers to hoard funds; in some cases, hiring and purchasing stops.