A surprise witness will take the stand in a highly-watched ballot tampering case – Bridgeport Mayor Joe Ganim. Attorneys made the announcement on Thursday, as testimony in the hearing finally got underway.

In deep blue Bridgeport, the Democratic primary almost always determines the city's next mayor. Ganim won the Sept. 12 contest by 251 votes, thanks to a huge advantage in absentee ballots.

But days later, a leaked security video called the victory into question. It appears to show Wanda Geter-Pataky, a Ganim campaign organizer and longtime city employee, stuffing stacks of papers into an absentee ballot box.

Now, Ganim's opponent, John Gomes, is asking a judge to overturn the results and order a new primary.

A second video posted last week shows a Gomes supporter visiting the same ballot box four times, and the same car stopping at a box three different times. Gomes insisted that everyone in the video was casting ballots for close relatives, which is legal in Connecticut. But Ganim's campaign accused his rival of "hypocrisy."

Bridgeport Police and the State Elections Enforcement Commission are investigating the videos, as well as how they were leaked.

Attorneys have spent weeks reviewing more than 2,000 hours of additional surveillance footage. Both sides expect to begin showing videos on Friday.

Gomes' legal team claimed it will prove "ballot harvesting."

"The number of absentee ballots that came in without stamps and without postmarks, substantially exceeds the number that we see on the videos actually dropping absentee ballots into the drop boxes," said attorney Bill Bloss.

But the city's lawyers said, not so fast.

"What we know definitively from the video is very little," said John Kennelly, who represents the Bridgeport Town Clerk. "What we don't know from the video is quite vast."

A small amount of that extra footage went missing as it was being copied over, a Bridgeport police sergeant testified on Thursday.

"There was one 24-hour period missing. One 12-hour period missing," said Sgt. Paul Grech, who oversees approximately 3,000 city surveillance cameras.

Ganim could take the witness stand as early as Friday or next Monday, but it's still unclear why he's testifying.

"I'm not going to talk about that here. I have a reason to do it," said Bloss. "We've seen on the videos that are now in evidence substantial non-compliance with state statutes by people who are affiliated, and supporters of his campaigns. So I'm going to ask the question."

Attorneys for the city called the move a publicity stunt.

"It seems a little theatrical … Joe Ganim, as the mayor of the City of Bridgeport, has absolutely no role in the election other than to cast his own ballot," said Kennelly. "I've watched 2,100 hours of video at this point – me and the people assisting me. And I haven't seen Joe Ganim on any of them."

Geter-Pataky is also scheduled to testify on Friday afternoon. But because of the pending investigations, lawyers expect her to assert the 5th Amendment and refuse to answer questions.

Gomes' legal team is also requesting a list of Bridgeport residents receiving housing assistance.

According to a state election complaint, a voter on Morningside Drive claimed that Geter-Pataky "promised her she can get her a Section 8 [housing] voucher if she votes for Ganim."

According to The Connecticut Mirror, e-mails reveal that a Bridgeport city employee was ordered to turn over a rental rebate program list to Geter-Pataky. A Ganim spokesperson insisted the move wasn't meant to target potential voters, but to ensure "security and safety issues so that way we can help direct the applicant on where to go to the building."

Testimony in the ballot trial is expected to run into next week. But even if the judge orders a new Democratic primary, it could not happen before Nov. 7 – meaning voters would have to go back to the polls after the general election.

Both men are on the November ballot, but only Ganim is listed as the Democratic candidate. Gomes is listed on a third-party line.