India could face as long as six months battling to ensure coal-fired power plants have enough fuel as the nation’s energy crisis escalates.

More than half the nation’s plants are on alert for outages after surging electricity demand and a slump in local coal output eroded stockpiles. Power stations had an average of four days’ worth of coal at the end of last month, the lowest level in years, and down from 13 days at the start of August.

“I don’t know whether I will be comfortable in the next five to six, four to five months,” Power Minister Raj Kumar Singh was quoted as telling The Indian Express in an interview published Tuesday. While demand does typically slow with cooler weather from mid-October, “it’s going to be touch and go,” he said.

In at least a portion of India’s coal fleet the situation has deteriorated in the past week, according to Singh. Coal plants accounting for between 40 gigawatts to 50 gigawatts of capacity currently have less than three days’ of fuel stocks, he told the newspaper. That compares to a total national coal capacity of about 203 gigawatts.

Read more: Energy Crisis Deepens in India as Power Plants Face Outages

Coal accounts for about 70% of India’s electricity generation, and consumption is forecast to rise in the next few years, even as Prime Minister Narendra Modi pushes for a massive increase in renewables. Like neighboring China, India is suffering from the impacts of a sharp surge in electricity demand, a squeeze on domestic mine output and surging prices of seaborne coal.

Government ministries are working with state-run Coal India Ltd. and NTPC Ltd., India’s largest power generator, to raise output from mines and to ensure demand is met, Singh was quoted as saying.

Coal supply will be prioritized to utilities that have made regular payments to coal companies, and that have been maintaining mandated levels of fuel stocks, according to the newspaper.