Construction of what would be North America's tallest building may move forward thanks to unions that not only want their workers to build it but are trying to put together a deal to help pay for it.

A group of union pension funds _ eager to provide work for union workers _ are in talks to loan $170 million to Irish developer Shelbourne Development Group so construction of the twisting 2,000-foot-high Chicago Spire can resume as soon as early next year.

The Spire, which won city approval and saw workers break ground in 2007, has sat dormant for a year since the global financial crisis triggered various fights involving bankers, the architect and the developer, bringing work to a standstill.

The loan would pay off the estimated $64 million loan made by Anglo Irish Bank and satisfy various liens to firms that have worked on the Spire, including one by a firm associated with architect Santiago Calatrava, who stopped working on the project, claiming the developer owed him more than $11 million.

Tom Villanova, president of the Chicago and Cook County Building and Construction Trades Council, said the money would come from an AFL-CIO pension fund and Union Life Insurance Co., and perhaps pension funds from various locals.

The reason, he said, is simple.

"This would be 7.5 million man-hours for my members and I have locals that have 30 percent unemployment," said Villanova, whose group represents two dozen unions with about 100,000 members. He said the project _ which Shelbourne said would take about four years to complete _ would mean work for as many as 1,000 union workers.

Villanova said the opportunity to invest comes at a good time for his group _ in large part because the city lost its bid to host the 2016 Olympics.

"We were interested in funding part of the Olympic Village," he said. But when the city lost the games, "This (the Spire) jumped into first place as a project we focused on."

Villanova didn't know exactly when an agreement could be reached. But he said he is "very optimistic and hopeful" that it'll happen.

He downplayed the risk of investing in a skyscraper that will house nearly 1,200 condos in a city that has been flooded with so many new condos that owners in some parts of the city have struggled to sell them.

For one thing, he said, unions have been making these kinds of loans for years. He said, for example, the AFL-CIO fund has invested more in Chicago _ about $1 billion _ than in any other city in the country.