ST. PETERSBURG — Mayor Bill Foster has thrown down the gauntlet and set a deadline for the group trying to force a vote to save the city's iconic Pier.

Foster has told the group voteonthepier.com that it has until June 11 to submit the almost 16,000 petitions needed to get its question on the Nov. 6 ballot.

"It's either put up or shut up,'' Foster said Thursday, noting that the group's leader had turned up at a recent City Council with three cartons that he said were filled with petitions.

"I support the efforts of the people to add this question on a ballot,'' he said. "That being said, it cannot be open-ended. We need to move forward. They have had two years to do it. It's just time.''

Tom Lambdon, the Safety Harbor man spearheading the group opposed to tearing down the current inverted pyramid for a $50 million replacement, is disinclined to be rushed.

"It's unrealistic to assume we can have everything we require within the next few business days," he said.

"It's a deadline for this election,'' he said. "It doesn't in any way affect our dedicated effort to get this petition drive successfully over the finish line in the next couple of months. We are auditing every single petition before we submit them to the clerk and supervisor of elections. It's such an important issue to us that we are leaving zero room for mistakes."

Lambdon said the group has collected a little more than 14,000 petitions.

Foster's decision to pressure voteonthepier.com appears to be part of a two-pronged strategy that includes a broad campaign to build support for the new Pier. Speaking at a meeting with the Tampa Bay Times editorial board, Foster expressed concern about "the lack of facts" surrounding the need to replace the current Pier. He talked about a website the city is about to launch and of upcoming sessions to get public input about how the new Pier should be developed. He handed out a brochure entitled, "Get the Facts!"

"When people are armed with the facts, they get it,'' he said later.

Foster said he set the June 11 deadline for Lambdon's petitions by working backward, taking into account the time needed for them to be processed and for the City Council to consider an ordinance to put the measure on this November's ballot.

In a May 24 letter to Lambdon, city clerk Eva Andujar said it could take several days for the petitions to be counted by her office before they are sent to the supervisor of elections. "Signatures must be verified and the number of required petitions must be confirmed before council takes action to place your question on the ballot,'' she said.

Foster said the City Council can consider an emergency ordinance if the June deadline is missed.

Lambdon is not worried.

"There's nothing in (the letter) that says if you don't meet this deadline that this is done," he said.

"We are in no hurry. … If we don't make this deadline … we are fully supportive of putting it on the next municipal ballot instead of burdening taxpayers with a special election."

The primary for the next municipal election is August 2013, with the general election in November. The city has announced that the inverted pyramid will close on May 31, 2013. Demolition is expected to take place in August.

Waveney Ann Moore can be reached at wmoore@tampabay.com or (727) 892-2283.