TIM WHITMIRE of the Charlotte Observer reports: A government watchdog group wants Charlotte to consider building an uptown arena atop an expanded Charlotte Convention Center -- a proposal the group claims could save $160 million.

But the plan floated Thursday by Citizens for Effective Government contains a number of major question marks. And one council member said it is unlikely to come before the City Council before it makes a Feb. 11 decision on business leaders' offer to front $100 million for a new arena.

CFEG leaders said they believe their proposal is viable whether or not the NBA's Charlotte Hornets -- who have applied to move to New Orleans -- play in the building.

They said they decided to bring their idea forward after city business leaders pitched an uptown arena Jan. 7, offering upfront cash in exchange for city-owned land and other benefits.

"If they're going to do this, is there a better idea? Can we do this better?" said CFEG treasurer Alan Wells, who said he has been honing his proposal for four years.

"The numbers are there, and the numbers work," CFEG president Lewis Guignard said.

Three council members attended the presentation: Don Lochman, John Tabor and Patrick Mumford. Each said afterward he was intrigued, but that the proposal would have to undergo greater scrutiny.

Lochman, the only council member to vote against having city staff consider the business leaders' proposal, said he doesn't think there's time to look at both proposals before the Feb. 11 deadline set by the business leaders.

"This is a backup plan," Lochman said. "There's no way we can do this in a month."

According to CFEG's plan, $160 million of the project would be financed with bonds, which would be repaid through a number of revenues, including the hotel/motel tax and a major donation from the private sector.

The arena would be built atop a 135,000-square-foot Convention Center expansion, across Brevard Street from the current center. In a CFEG drawing, the arena juts over Brevard and Caldwell Streets, its west wall coming flush against the wall of the current convention center.

CFEG said its proposal saves money by using existing city-owned land, eliminating the need for the city to buy land to build an arena, and by combining what would be two separate construction projects, with separate sets of infrastructure costs, into one.

According to CFEG, building an arena and convention center expansion together would cost $220 million. Built separately, the group said, the projects could currently cost $387 million -- $125 million for the convention center expansion and $262 million for the arena.

However, Mike Crum, head of the city's Coliseum and Convention Center Authority, said Thursday that the only price tag ever attached to a convention center expansion was $200 million to $250 million, for an expansion that would be designed beginning in 2010 and completed by 2013.

CFEG leaders said the city also could lease air rights over the expanded Convention Center to a private developer who would build and operate an arena. Though Wells said three developers had expressed interest in such a project, he declined to name them.

Wells' proposal is not a new one. He brought it before the city's New Arena Committee, which met in 1998 and 1999, committee member Anthony Fox said.

"It was shot down fairly early and fairly quick," recalled Fox, a Charlotte lawyer.

Fox said committee members concluded that, rather than saving money, building an arena on top of an expanded convention center would be more expensive.

Jim Schumacher, the city's chief engineer, agrees.

"The reality of what you have to do to make that work (allowing the convention center to support the weight of an arena) would not provide savings, but would cost extra," he said.

There are other unanswered questions about CFEG's proposal:

? The proposal would decline the $100 million the heads of Wachovia, Bank of America and Duke Energy have offered for at least two pieces of city owned land (the current Coliseum and old civic center) and up to $50 million from the sale of naming and beverage rights and deposits on premium seats.

Instead, under CFEG's proposal, the city would ask the businesses to simply donate $50 million, then would seek to sell the Coliseum and Convention Center land for $40 million that could be used for the arena.

Nelson Schwab, who has helped organize the business leaders' proposal, did not return a message seeking reaction to CFEG's idea.

? CFEG leaders said they were told by the Kansas City design firm Ellerbe Becket that an arena design prepared for last June's failed referendum on an uptown arena could be modified relatively easily for placement atop a Convention Center expansion.

Ellerbe Becket spokesman Stuart Smith said Thursday he was unable to reach the architects who have worked on the proposed Charlotte arena, but added that the firm has designed and built three arenas over existing structures: Boston's Fleet Center, New York's Madison Square Garden and Washington's MCI Center. All sit atop train stations -- not convention centers.

? The proposal also relies on income from a parking deck for the under-construction Westin Hotel, across Stonewall Street from the Convention Center, to pay $25 million of the bonds that would be floated for the arena/Convention Center expansion.

But Crum said parking deck revenues are already dedicated to repaying money borrowed to build the hotel and parking deck.