Accusing trade unions of standing in the way of minority hiring objectives, City Council yesterday declared the $700 million Convention Center expansion open to nonunion contractors and workers - an unprecedented gesture in a city dominated by organized labor.

Citing the construction industry's repeated failures to meet minority hiring goals on public projects and the unions' refusal to disclose the racial makeup of their memberships, Council voted to amend the Convention Center's operating agreement to allow nonunion workers, to help increase minority participation.

Such a change would face final Council approval Thursday, and Gov. Rendell would have to agree to it.

Mayor-elect Michael Nutter appeared to support Council's action yesterday.

"Clearly, that amendment represents the frustration that many of us have felt in creating opportunities for African Americans and Latin Americans in terms of access to the construction trades and participating in all the tremendous construction activity in Philadelphia," said Nutter. "We must create a more diverse workforce in the construction industry in the city."

The very thought of allowing nonunion contractors on a major public works project in Philadelphia stunned longtime observers.

"Wow," said public relations executive A. Bruce Crawley, one of the city's leading critics of the union's efforts at hiring minorities. "Wow."

"This is very encouraging for African American contractors who would simply like not to be excluded from the work," he said.

Patrick Gillespie, business manager for the Philadelphia Building and Construction Trades Council, said such a requirement would endanger the project labor agreement the 42 local unions he represents are negotiating with the Convention Center Authority. Such agreements are common before major projects - they set the standards of work and pay, usually require union labor, and are meant to avoid job disruptions.

"I wouldn't enter into a deal where it would allow people to work nonunion. What's the point of that?" he said. "To lose the protection of collective bargaining?

"People can amend things there [in Council], I guess, but they cannot amend our world."

Albert Mezzaroba, Convention Center president and CEO, said he thought approval of the agreement by Council should allow the project to move forward.

Gillespie's failure to produce statistics on the racial makeup of the council's unions - he also would not provide that information in 2003, when the stadiums for the Eagles and Phillies were being built - prompted Councilman Frank DiCicco to offer the amendment.

"With there being no movement from the building trades . . . they essentially left this Council no choice," said Councilman W. Wilson Goode Jr. "And thus begins an era ending the monopoly of the training and supply of construction labor."

It all began peacefully as Council members praised new and increased hiring goals for the Convention Center expansion - 50 percent of the jobs and contracts are to go to minorities and women. But Councilman Darrell L. Clarke and others said that while the city had progressed in awarding more contracts to minority-owned firms, the makeup of the construction trades continually frustrated goals for hiring individuals.

The hearing turned sour as Council members questioned Gillespie, pressing him for statistics, even taking an hour-long break and offering him use of the clerk's office to make phone calls. Gillespie told Council members he didn't know - and couldn't find out on short notice - the racial makeup of the council's 42 local unions.

"We've been doing this for years - round and round and round and round," said Councilwoman Marian Tasco. "We ask all the time what is the membership of the trades, and we never get an answer."

That's when DiCicco stepped in with an amendment to the operating agreement involving the city, state and authority that requires Council approval.

"It's been a long time coming," said DiCicco. "In the 12 years I've been here, nothing has really changed regarding minority hiring."

DiCicco and Gillespie are both members of the Convention Center's board.

Gillespie said he resented Council's insinuations, and said the building trades council did meet hiring goals consistently.

"Everything you've done here today is a canard," he told DiCicco. "There's some perception here that the building trades are entirely made up of white people."

Gillespie said about 300 of 400 apprentices taken from the Philadelphia School District were minority.

Tom Muldoon, president of the Philadelphia Convention and Visitors Bureau, told Council that six major events in 2010 had to be canceled because of delays. The expansion project has had repeated delays and is now supposed to be completed by early 2011.

"We're beginning to lose credibility," Muldoon said.