Colorado's utility regulators are up for review by state lawmakers.

An audit of the Public Utilities Commission is expected Tuesday.

Republicans called for the audit because of disputes over the PUC's actions on cases involving taxicabs, telecommunications and power plants.

One of the PUC's high-profile cases involved the conversion of some Xcel Energy coal-fired power plants to natural gas. The mining industry says two PUC members helped draft the law that led to the proposal, compromising their impartiality.