An increasingly hostile political climate, coupled with the prospect of rocketing costs and a drawn-out permit fight, has rekindled prospects of the Warriors trying to team up with the Giants to shift the site for their proposed waterfront arena down to the parking lot across from AT&T Park.

Although the two teams have not had direct talks, both sides are said to be open to discussing the idea.

"It's still full steam ahead on Piers 30-32, but we have always and will always consider backup plans," said Warriors spokesman P.J. Johnston.

Mayor Ed Lee has been reluctant to push any alternative until he gets the go-ahead from the Warriors. But in a statement, mayoral press secretary Christine Falvey said her boss "looks forward to sitting down again very soon with the Warriors' ownership to discuss next steps for the arena and Piers 30-32 site."

She said "bringing the Warriors home to San Francisco and building a new waterfront basketball and entertainment pavilion ... remain a priority" for Lee.

Although the Giants' Parking Lot A across McCovey Cove from the ballpark lacks the breathtaking dazzle of Piers 30-32, building a 17,000-seat arena there would still boost the Warriors' overall value. It would also be a sufficiently central location for hosting the 150 events a year, in addition to basketball games, that would be needed to make the arena financially viable.

Taking the arena off Piers 30-32 - and out of what is fast becoming one of the city's toniest neighborhoods - could also cut down on objections from nearby residents, plus ease concerns about traffic along the Embarcadero.

In other words, from the Warriors' perspective, it would get the job done in our lifetime and would still put them on the waterfront.

"It works just fine," summed up one source who has worked on the project, but who declined to speak for the record because of the sensitive nature of the discussions.

The move could also help the Giants sell voters on their own plans to build a development around their ballpark, including two apartment towers more than 30 stories tall. And it could boost plans for a 2,100-car parking garage the Giants need to build to make up for the spaces they would lose by building on their parking lot.

Giants President Larry Baer declined to comment.

One big reason for the possible southward shift is the emergence of a June ballot measure that would require voter approval for all waterfront developments taller than the current 48-foot limit. The Warriors intend to build condos and a hotel across from the Piers 30-32 site to help pay for the arena, but a couple of polls in recent weeks show they could be a deal-killer with voters.

Those extras might not be needed if the arena were built on the Giants' parking lot instead of Piers 30-32, where the estimated rehabbing cost has doubled to $180 million.

One thing is certain - the most prominent opponents of an arena at Piers 30-32 would be a lot happier if it were built across from the ballpark instead.

"I am very open to Lot A for a Warriors arena," said former Mayor Art Agnos. "The leadership of the city should get the Warriors and Giants together to work out a mutually satisfactory business agreement.

"And the sooner they do it, the better."

Former Board of Supervisors President Aaron Peskin, one of the most vocal opponents of "Wall on the Waterfront" developments, said he would support an arena in the Giants parking lot "without hesitation or reservation."

"It would be perfect," Peskin said.

The idea would be to get a deal done in time for the November ballot, or possibly in a special election early next year.

The big question is whether the Giants and Warriors owners - who fought over a previous plan to build an arena down the waterfront from AT&T Park at Pier 50 - can come to an agreement over who gets what out of the deal.

Political insiders tell us the Giants question whether Lee has the stomach to stand up to the Warriors in the negotiations, given the importance he has placed on luring the team from Oakland.

They're hoping Sen. Dianne Feinstein, given her stature, will be invited in to make sure they are treated fairly.

In any event, the dance has begun, and it's just a question of who's willing to make the first call.