AEG President Tim Leiweke (r) and Mayor Antonio Villaraigosa (ctr) share a laugh while signing an implementation agreement to modernize the Los Angeles
AEG President Tim Leiweke (r) and Mayor Antonio Villaraigosa (ctr) share a laugh while signing an implementation agreement to modernize the Los Angeles Convention Center and build Farmers Field during a press conference outside the Los Angeles Convention Center on Wednesday, Oct. 3, 2012. (Andy Holzman/Staff Photographer)

Even the most optimistic city leaders admit numerous hurdles remain in L.A.'s bid to bring back professional football and revamp the Los Angeles Convention Center.

But as officials and Anschutz Entertainment Group executives gathered downtown Wednesday at a ceremony to sign off on and celebrate the project deal, those concerns seemed far off. The mood was upbeat, and the gathering festive.

Despite the lack of a team, the proposed sale of AEG by its parent company and another possible lawsuit over the stadium, city officials believe they've shown they have the political commitment to bring the National Football League back to Los Angeles.

"We're closer than any time since the Rams and Raiders left this great town," Mayor Antonio Villaraigosa said.

The event at the Los Angeles Convention West Hall, which would be demolished and relocated to make way for the stadium, celebrated the signing of a 1,000-plus page financial agreement between the city and AEG, which spells out the terms of the public-private partnership to build the stadium.

Under the agreement, the city will issue bonds to pay the $314 million cost of the new convention center hall. The bonds will be repaid through a variety of means, including a special tax imposed on AEG's stadium and L.A. Live site.

AEG cannot start construction on the stadium until it has signed a lease with an NFL team.

At the ceremony, Villaraigosa praised city negotiators, casually mentioned a recent meeting with NFL Commissioner Roger Goodell, and shrugged off news of a possible second lawsuit pertaining to the stadium.

"That's expected," Villaraigosa said of legal threats. "A project of this magnitude, there is always going to be a lawsuit."

Continuing its resistance to the stadium, a group of downtown residents plans to file a lawsuit challenging AEG's environmental impact report for the stadium project and the City Council's approval of the report, Becky Dennison, co-director of the Los Angeles Community Action Network, wrote in an email this week.

At the council hearing Friday when the EIR was approved, numerous speakers complained the city wasn't doing enough to ensure AEG reduced the project's negative effects on air quality and traffic.

The Play Fair at Farmers Field Coalition is also part of a lawsuit challenging Senate Bill 292, which was special legislation passed for AEG that expedites any lawsuits challenging the project. The coalition wants AEG to establish a multimillion-dollar trust to fund low-incoming housing.

AEG president Tim Leiweke, the project's chief architect, dismissed opponents and expressed confidence that the project will come to fruition.

"There are those that don't support this. I call them `cavemen' and `cavewomen,' Leiweke said. "But I'd like 100 percent of the people to like our project."

He added: "We're going to get a team, and we're going to get this stadium built. We promise."

Legal challenges aside, much of the city's work on the stadium is finished in the short term.

"The deal is structured so once it is approved, the work is really on AEG," said Miguel Santana, the city's chief administrative officer.

AEG President Tim Leiweke (left) joins Mayor Antonio Villaraigosa and other officials for a photo with a rendering of Farmers Field following a press
AEG President Tim Leiweke (left) joins Mayor Antonio Villaraigosa and other officials for a photo with a rendering of Farmers Field following a press conference outside the Los Angeles Convention Center Wednesday, Oct. 3, 2012. The group gathered Wednesday to sign an implementation agreement for the modernization of the Convention Center and the building of Farmers Field. (Andy Holzman/Staff Photographer)
"It's really up to them to find a team and put the pieces in place."

But city planners will continue to refine designs for the public spaces around the convention center and stadium.

On Wednesday, Villaraigosa responded to criticism that the city should have spent more money and time on the new convention center hall design. Some architects have called for a redesign and criticized the way the hall extends 1,000 feet over Pico Boulevard.

"We have to protect the taxpayers," Villaraigosa said, explaining why more costly designs weren't considered.

Now, city officials say, it's up to AEG to find a team. With their work over the last two years, they believe NFL officials know there is political support in L.A. for a team to return.

"Everyone is really optimistic," Santana said. "There is a lot of momentum."

dakota.smith@dailynews.com

818-713-3761

twitter.com/dakotacdsmith