Companies and workers in the U.S. will increasingly lose out to competition from overseas during the next three years, according to a survey of Harvard Business School alumni.

More than two-thirds of about 10,000 graduates of the school in Boston, said that U.S. companies will become less able to compete internationally or pay high wages and benefits, according to the report released today.

Other nations are challenging the U.S. with well-trained workers who garner lower wages, the authors said. Survey respondents in the manufacturing industry, who are in the prime of their careers or are working in companies with international rivals, were the most pessimistic about the U.S.’s prospects, said the authors, Michael Porter and Jan Rivkin, both professors at the business school.

“Business leaders and policy makers in America must find ways for Americans to work smarter and more productively than workers who are paid lower wages overseas,” they said in the report.

Almost 80 percent of respondents said the U.S. is falling behind other countries in the effectiveness of its political system and primary and secondary education, the report said. More than 60 percent said the U.S. is behind other nations in the complexity of its tax code and its infrastructure.

The report summarized results from 9,750 respondents to a survey conducted in October. It was designed as a census of Harvard Business School alumni, and calculations of a margin of error don’t apply to it, the authors said.