Sen. Kyle Loveless, R-Oklahoma City, said he voted against the bill because the state could stand to lose $40 million in private pledges to help complete the center if it is placed under a different agency.
A bill authorizing a $40 million bond issue for the center failed by one vote last year in the Senate.
Treat said he is concerned by the findings of a state audit last year that criticized the authority for choosing highest-cost options when funding wasn't secure. Treat filed a bill last year to put the center under the state Tourism and Recreation Department; it passed the Senate but failed in the House of Representatives.
The American Indian Cultural Center and Museum project has benefited from three previous state bond issues totaling $63 million, as well as $14.5 million in federal funding and $4.9 million and 250 acres of land from Oklahoma City.