SALT LAKE CITY — Mayor Ralph Becker wants to spend $15 million now to begin designing the Utah Performing Arts Center, saying historically low interest rates and a favorable construction climate will save the city money in the long run.

The problem, though, is that proposed revenue sources for the $110 million project won't be available until 2016, and some of them — including selling naming rights for the theater — aren't a sure thing.

Becker has asked the Salt Lake City Council to issue up to $18 million in short-term bonds to design the 2,500-seat theater planned for the east side of Main Street between 100 South and 200 South.

City officials have proposed scheduling interest-only payments on the bonds until 2016, when bonds for EnergySolutions Arena are paid off and additional property-tax revenue materializes from the city block where the theater is proposed to be built. The majority of those funds would then be put toward making bond payments for the theater.

Ben McAdams, the mayor's senior adviser for intergovernmental affairs, said design of the theater would take at least a year. And that doesn't include the three to six months needed to solicit designs through a request-for-proposals process.

"The biggest risk in this funding model we've identified right now is interest rates and construction costs," McAdams told the City Council during a work session Tuesday.

Even modest increases could boost the project's price tag by 10 percent to 20 percent, he said.

"There really is a sense of urgency that we move ahead as quickly as possible," McAdams said.

The City Council is expected to vote Dec. 6 on whether to issue the short-term bonds.

City officials say feasibility and economic-impact studies show there is pent-up demand for a theater capable of hosting first-run touring Broadway shows.

Several local arts groups disagree, and they worry such a theater would do them financial harm.

Greg Gellman, executive director of Kingsbury Hall, expressed his concerns in a letter to the City Council on Tuesday.

"A new theater will be in direct competition with Kingsbury Hall, the Capitol Theatre and Abravanel Hall, with potential adverse impact on all three," Gellman wrote.

Kingsbury Hall, he wrote, would have the "most exposure to impact" from the new theater.

"While all performing arts organizations will be competing for ticket buyers and the Capitol Theatre competing for rental clients with the new facility, Kingsbury Hall will be in direct competition for programming," Gellman's letter states.

The Pioneer Theatre Co. also has voiced its objections to the theater.

"There's a point where you have to agree to disagree," said Helen Langan, a senior adviser to the mayor. "All the data we have say one thing, and (some local arts groups) have a different opinion about it."

Last month, Emmy-winning composer Kurt Bestor and Wells Fargo executive David Golden formed Friends of UPAC, a group of arts organizations, patrons and business leaders who support plans for the Utah Performing Arts Center.

Several of those supporters spoke in favor of moving forward with the project during a public hearing Tuesday night. A handful of others echoed Gellman's concerns.