A City Council vote scheduled for Thursday on a controversial proposal to allow nonunion contractors to work on the $700 million expansion of the Convention Center will be put off to give Gov. Rendell and state leaders a chance to forge a compromise with the city and unions.

Three Council members confirmed tonight that they expected to come back next week to ratify a deal to be negotiated by Rendell, black legislative leaders, city officials, the unions, and the Convention Center Authority.

The proposal to allow nonunion work on a municipal project - in a city where labor unions hold much influence over political decisions - arose during Council's Dec. 6 meeting, when members voted to amend the Convention Center's operating agreement. Their vote was an expression of what they said was their frustration at the unions' inability to meet minority-hiring objectives.

In addition to roiling the political waters, Council's unprecedented decision brought concerns from the Convention Center Authority, which feared that construction would be delayed, jeopardizing bookings.

Councilmen Brian J. O'Neill and W. Wilson Goode Jr. and Council President Anna C. Verna confirmed the negotiations with the governor.

"We've got to get this thing resolved," said O'Neill, who will be involved in negotiations. "And we have to do it the right way."

Rendell could not be reached for comment tonight.

O'Neill, however, said the first negotiation session would be held Monday in Rendell's Center City office. Also expected to be involved in the negotiations are State Sen. Anthony H. Williams and State Rep. Dwight Evans, both Democrats from the city.

Goode said Rendell had to act because approval of the agreement was heading for an 8-8 deadlock on the 17-member Council, which would kill any action until next year. (Councilman Jim Kenney has abstained because he works for Vitetta Architects & Engineers, which has a contract for the Convention Center expansion.)

Convention Center officials had hoped to send out bids in January and start construction as early as March, with summer 2010 as the targeted completion date.

Yesterday afternoon, Mayor-elect Michael Nutter told reporters he was pushing Council to approve the nonunion amendment. But by early evening, he said he was aware that Rendell would intervene.

Council has long criticized the Philadelphia Building and Construction Trades Council of failing to bring significant numbers of minorities into their ranks. Complaining that those unions routinely refused to disclose the minority makeup of their membership, Councilman Frank DiCicco last week offered an amendment to the center's operating agreement to open the project up to nonunion workers. The amendment was criticized by the unions: Building-trades chief Patrick Gillespie called it "death language" for unions.

DiCicco's chief of staff, Brian Abernathy, would not commit tonight on the latest development.

Frank Keel, a spokesman for electricians' union chief John J. Dougherty, praised the efforts, issuing a statement tonight that read: "The good news is that more rational voices prevailed and everyone is optimistic that we can achieve an agreement that will ensure ample minority participation in the Convention Center expansion project."

Should a deal be worked out, Council might be required to return Dec. 27 for a final vote.

Contact staff writer Jeff Shields at 215-854-4565 or jshields@phillynews.com.

Inquirer staff writer Marcia Gelbart contributed to this article.