Millions of Texans have gone days without power or heat in subfreezing temperatures brought on by snow and ice storms. Limited regulations on companies that generate power and a history of isolating Texas from federal oversight help explain the crisis, energy and policy experts told The Texas Tribune.

While Texas Republicans were quick to pounce on renewable energy and to blame frozen wind turbines, the natural gas, nuclear and coal plants that provide most of the state’s energy also struggled to operate during the storm. Officials with the Electric Reliability Council of Texas, the energy grid operator for most of the state, said that the state’s power system was simply no match for the deep freeze.

“Nuclear units, gas units, wind turbines, even solar, in different ways — the very cold weather and snow has impacted every type of generator,” said Dan Woodfin, a senior director at ERCOT.