Legislators said Friday that Attorney General George Jepsen, a staunch ally of labor, effectively has killed a legislative priority of the Connecticut AFL-CIO by advising them that federal labor law appears to pre-empt the state from passing a “captive audience” bill.

The House of Representatives passed the controversial bill two weeks ago, 78 to 65, after an 11-hour debate in which the key sponsor, Rep. Zeke Zalaski, D-Southington, relied on a letter from Jepsen assuring him that the bill was legally sound.

An unhappy Zalaski said that Jepsen visited him earlier this week to inform him that additional legal research by his staff concluded that the state cannot bar employers from requiring employees to attend a meeting called to discuss religious or political matters.

“I just said, ‘You couldn’t tell me that before I did the bill?’ ” Zalaski said. “Come on, I gave it 11 hours.”

Sen. Edith G. Prague, D-Columbia, the co-chairman of the Labor and Public Employees Committee, said that the Senate will not take up the bill in light of Jepsen’s warning that the bill might not be legally defensible.

“That’s it,” she said. “We’re not doing the bill.”

But Senate President Pro Tempore Donald E. Williams Jr., D-Brooklyn, said the Democratic majority had not made “a hard or final decision” on whether Jepen’s advice was reason to give up on the legislation, although the he acknowledged that prospects remain tenuous with a number of undecided votes.

Jepsen said the earlier letter on which Zalaski relied was not a formal legal opinion.

“My letter, dated May 5, was simply an affirmation of a prior, informal policy position and advice given in 2007 by former Attorney General Richard Blumenthal,” Jepsen said in a statement released by his office.

“I am aware that substantial and serious legal questions about preemption have been raised concerning the positions taken in both the May 5, 2011 and (Blumenthal’s) March 14, 2007 letters,” he said. “My office is reviewing these legal issues.  It would be inappropriate for me to comment further publicly about it at this time.”

Jepsen initially declined comment Friday, because his office might have to defend passage of the bill. But after Prague said the measure was dead, Jepsen his office had been approached before the House debate and affirmed Blumenthal’s earlier view that the bill was legally sound.

The Connecticut Business and Industry Association circulated its own legal opinion that National Labor Relations Act pre-empts the state from addressing the issue. Jepsen ordered his staff to conduct a deeper review.

“I’m never afraid to take a second look,” Jepsen said

Still, he declined to share exactly what he told legislators after that additional review.

Jepsen’s position defuses a difficult political situation for the Senate and Gov. Dannel P. Malloy. With the passage of a paid sick days bill, the business community had stepped up its opposition to the captive-audience bill, calling it a blow to Connecticut’s image among employers.

John Olsen, the president of the Connecticut AFL-CIO, said the statewide federation of unions would continue to press for passage in the Senate, saying a legal opinion is statement of what might happen in the fact of a court challenge, not a certainty.

“We believe the bill, from all kinds of standpoints, is defensible,” Olsen said.

Mark is the Capitol Bureau Chief and a co-founder of CT Mirror. He is a frequent contributor to WNPR, a former state politics writer for The Hartford Courant and Journal Inquirer, and contributor for The New York Times.