Former Mayor Bob Jackson may sue the city because he was disqualified from the Nov. 3 election.
Jackson said city employees made a series of mistakes that led to his disqualification to run, and the resulting disenfranchisement of voters.
"It's essentially about the people's right to make a choice," Jackson said.
Jackson was challenging incumbent Mayor Pat Gerard, who defeated him in 2006 in a close and heated race.
City Clerk Diane Bruner notified Jackson on Thursday that he would be disqualified because he failed to sign a loyalty oath.
In the oath, candidates vow to uphold the Constitution and affirm they are qualified to hold the office.
The Pinellas County Supervisor of Elections Office noticed the missing signature on Jackson's oath after Bruner submitted the forms.
Bruner, who initially informed Jackson that he had qualified, made the decision to disqualify him after requesting an opinion from an attorney with the state Division of Elections.
Bruner said she failed to notice the missing signature because she didn't do a thorough review.
Another city employee, Donna Givens, who had notarized the oath even though it was missing Jackson's signature, has also admitted her mistake.
Tuesday, Jackson's attorney, Robert G. Walker, submitted a letter to Bruner that outlined those and other alleged errors. He said the city had the responsibility to right Jackson's situation, which occurred through the city's "own defaults and inactions."
The Clearwater lawyer said Jackson didn't bear responsibility for the missing signature. He left the signature line blank on the oath only because that signature had to be provided before a notary, Walker said.
"In Mr. Jackson's case, there was no error on his part," Walker wrote.
Walker's letter also contended that Bruner handed the loyalty oath to Donna Givens, the receptionist who notarized the document, without asking Jackson to sign it. Givens, however, recalled that Bruner did tell Jackson he needed to sign the form.
It's ultimately the responsibility of a candidate to make sure his or her forms are complete, said Jennifer Krell Davis, spokeswoman for the Florida Division of Elections. Candidates who disagree with qualification decisions can seek remedies in court, she said.
When asked Tuesday if he was considering suing the city, Jackson replied, "That's why I hired a lawyer."
So far, one couple, Robert and Christel Hunsicker, have written City Hall to complain about the disqualification.
"As a result of (Bruner's) actions, because of her negligence, we as the citizens of Largo don't have a choice in this election," said Robert Hunsicker on Tuesday afternoon.
Meanwhile, Commissioner Mary Gray Black has weighed in on the issue, requesting a special meeting to discuss what she interpreted as a violation of elections law, according to an e-mail to the St. Petersburg Times. Other commissioners declined her request, City Manager Mac Craig said.
Black also asked Bruner to provide copies of all seated commissioners loyalty oaths, writing that, since Jackson's disqualification, she had become "increasingly concerned" about whether members of the commission have met all the qualification requirements.