HOUSTON  The natural gas industry has enjoyed something of a winning streak in recent years. It found gigantic new reserves, low prices are encouraging utilities to substitute gas for coal, and cities are switching to buses fueled by natural gas.

But its luck has run out in Washington, where the industry is having trouble making its case to Congress as it writes an energy bill to tackle global warming.

For all its pronouncements that gas could be used to replace aging, inefficient coal-fired power plants  and reduce greenhouse gas emissions in the process  lawmakers from coal-producing states appear committed to keeping coal as the nation’s primary producer of power.

Those influential lawmakers, from both parties, say that new technologies under development to capture and bury emissions of coal are a better bet than gas for long-term solutions to climate change.