About 10,000 of those jobs have disappeared since, according to the association, as wind companies have been buffeted by weak demand for electricity, stiff competition from cheap natural gas and cheaper options from Asian competitors. Chinese manufacturers, who can often underprice goods because of generous state subsidies, have moved into the American market and have become an issue in the larger trade tensions between the countries. In July, the United States Commerce Department imposed tariffs on steel turbine towers from China after finding that manufacturers had been selling them for less than the cost of production.

And now, on top of the business challenges, the industry is facing a big political problem in Washington: the Dec. 31 expiration of a federal tax credit that makes wind power more competitive with other sources of electricity.

The tax break, which costs about $1 billion a year, has been periodically renewed by Congress with support from both parties. This year, however, it has become a wedge issue in the presidential contest. President Obama has traveled to wind-heavy swing states like Iowa to tout his support for the subsidy. Mitt Romney, the Republican nominee, has said he opposes the wind credit, and that has galvanized Republicans in Congress against it, perhaps dooming any extension or at least delaying it until after the election despite a last-ditch lobbying effort from proponents this week.