An association of independent power producers is expected today to cast doubt on claims by Northern Pass that its transmission line project will create 1,200 construction jobs.

The New England Power Generators Association, a Boston-based organization that opposes Northern Pass, plans to present its own analysis of the jobs attributed to the Northern Pass project.

“Our report will show that it has a small employment impact,” said Sandi Hennequin, vice president of the group. “Obviously in this environment, everyone’s talking about jobs.”

Northern Pass spokesman Martin Murray said the expert who studied the project’s economic impact, New Hampshire economist Dr. Lisa Shapiro, used generally accepted economic models to make her projections.

“We certainly stand by the results of that study,” Murray said.

In 2010, Northern Pass completed a report that detailed the economic impact of its proposed 180-mile transmission line from Pittsfield to Deerfield.

The line would bring electricity generated by HydroQuebec into the New England power grid.

Last April, Shapiro released a subsequent report, paid for by Northern Pass, that estimated the $1.1 billion project will create between 1,100 and 1,300 jobs per year from 2013 to 2015, the primary construction period.

The Power Generators Association report, written by Dover economist Brian Gottlob of PolEcon Research, is expected to dispute those findings.

“Our report does spend time talking about the percentage of jobs that would be for New Hampshire people,” Hennequin said.

Northern Pass’ initial 2010 report said between one-quarter and one-third of construction costs would be spent locally. It also said that most New Hampshire jobs would be in tree harvesting, site work and construction, including electrical, professional and technical services.

The Power Generators Association has been on record against Northern Pass, complaining that the potential use of eminent domain creates an unfair advantage for a competitor.

“We’re more than willing to compete. It has to be the same rules and a level playing field,” Hennequin said.

Murray said the organization represents fossil fuel-burning plants, including natural gas, that could be displaced by Northern Pass.

“If you put new, cleaner and economical energy in the marketplace, it’s going to replace something else,” he said.

The Power Generators Association has scheduled a news conference for 1 p.m. today at the Dupont Group offices in Concord to release its findings.