Did a Pennsylvania hearing examiner face "undue political pressure," causing him to change his opinion on hearing a dispute involving whether union carpenters and Teamsters had been improperly barred from the Convention Center's workforce?

Gov. Wolf and Attorney General Kathleen G. Kane are being asked "to order an immediate investigation into this matter to determine whether any undue political pressure was applied that would make Pennsylvania Labor Relations Board hearing examiner [Jack E.] Marino suddenly reverse his prior decision."

The request came via a letter from two union leaders whose members - stagehands and laborers - gained jobs at the center after the carpenters and Teamsters were no longer permitted to work.

Marino could not be reached for comment.

"The letter has been received and is being reviewed," a spokesman for the governor said via e-mail without further comment. Kane's office did not respond to requests for comment.

In March, Marino wrote a letter saying he would dismiss complaints - primarily on technical grounds - by the Metropolitan Council of Regional Carpenters and the International Brotherhood of Teamsters, which said they had been improperly shut out of work last May at the Convention Center.

On Thursday, Marino reversed course, saying he would hear arguments in the case.

The carpenters and Teamsters had been two of six unions working at the center. After they lost jurisdiction, their work was taken over by the four remaining unions, particularly stagehands and laborers.

"This past Friday, without provocation, Mr. Marino inexplicably reversed his previous decision ... despite no new information or evidence having been provided to him, as far as we know," wrote Michael Barnes, business manager for Stagehands Local 8, and Ryan N. Boyer, business manager for the Laborers District Council.

Carpenters spokesman Martin O'Rourke said the union would have no comment on the stagehands' and laborers' request for an investigation.

Monday was a busy letter-writing day for Barnes, Boyer, and the leaders of two other unions who work at the center - John "Johnny Doc" Dougherty, business manager for Electricians Local 98, and Sam Malone, business manager of Ironworkers Local 405. They sent letters to Democratic leaders in response to a letter written to them by the Carpenters union dated April 3.

In that letter, Edward J. Coryell, who heads the Carpenters' regional group, asked the Democratic National Committee not to hold events at the Convention Center during its presidential convention in July 2016.

"We ask that you join us now in our struggle to stop [the center] from unfairly locking our members out," Coryell's letter says, "and not allowing them to return to their jobs and earn a living."

The carpenters and Teamsters lost the right to work at the center because their leaders did not sign a customer-satisfaction agreement by a management-imposed deadline, although both signed a few days later.

In response, the leaders of the other unions wrote, "The Carpenters' refusal to sign the new agreement was their decision and their decision alone. We would be greatly disappointed if leaders of the Pennsylvania Democratic Party chose to boycott the Convention Center - resulting in the potential loss of labor hours and income for our hardworking members."

On Friday, representatives of the Carpenters and Teamsters unions had said they were pleased with Marino's reversal. But Barnes, Boyer, and Dougherty were not, nor were members of the city's hospitality community. They had particularly blamed the carpenters for the steady loss of bookings, saying the carpenters caused "hassles" requiring convention-show exhibitors to hire unnecessary workers.

"Since the four unions signed the new customer-satisfaction agreement that was offered to all of us, hotel rooms have been filled, there have been a record number of new convention bookings, and the Democratic National Convention and the pope are coming," wrote Dougherty.

Convention Center chief executive John McNichol wrote in an e-mail Friday: "Many customers have been savvy enough to include provisions in their agreements that, if the carpenters return to the building, they have the right to cancel their events."

On Monday, McNichol said contract escape clauses don't actually use the word carpenters, but refer generally to changes in conditions.

"It's different language," McNichol said Monday, "but the intent is very clear."